Physics: Practice Questions Flashcards
Make Sir Isaac proud.
Kinematics & Motion
Unit Question:
Definition of a Meter
Since 1983 the standard meter has been defined in terms of the distance light travels in 1/(3 x 10^8) seconds.
Examples of Vectors
- Vectors are quantities that have both a magnitude (numerical value) and a direction.
- Examples of quantities that are vectors include displacement, velocity, momentum, and force.
Provide the name of the scalar quantity associated with each of the following vector’s magnitude:
* Displacement
* Velocity
Answer: Distance is the scalar quantity of displacement’s magnitude; speed is the scalar quantity to velocity’s magnitude.
Give the term that describes the speed and direction of an object.
Answer: Velocity
Solve:
If the displacement, x, of an object is related to its velocity, v, by the equation x = Av, determine the physical quantity represented by A.
- Answer: t for “time” (displacement = velocity * time)
Examples of Scalars
- Scalars are quantities that have a magnitude but no direction.
- Examples of scalars include time, mass, energy, speed, distance.
Solve:
Which one of the following four outcomes is true when a 6.5-gram feather and 2.5-kilogram ball are in free-fall motion assuming no air resistance after being released from the same height at the same time?
- The ball will strike the ground before the feather.
- The feather will strike the ground before the ball.
- The feather and the ball will strike the ground at the same time.
- There is not enough information to determine the outcome.
- Answer: 3. The feather and the ball will strike the ground at the same time.
(Any object dropped from the same height, regardless of mass, will strike the ground at the same time in the absence of air resistance.)
Solve:
The average distance from the sun to Jupiter is approximately 779 million kilometers.
To the nearest minute, calculate the time it takes for sunlight to reach Jupiter.
- Answer: 43 minutes
Solve:
A group of students is traveling 100. miles to Walt Disney World to participate in the academic challenge. The group completes the first half of the trip with a speed of 65.O miles per hour and the second half with a speed of 75.0 miles per hour.
To three significant digits, determine in miles per hour the average speed of the trip.
- Answer: 69.6 (miles per hour)
Solve:
To three significant digits, calculate in meters per second Usain Bolt’s average speed when he set the world record in 2009 by winning the 100-meter dash in a time of 9.58 seconds.
- Answer: 10.4 meters per second
Solve:
To three significant digits, calculate in meters per second Florence Griffith-Joyner’s average speed when she set the world record in 1988 winning the 100-meter dash in a time of 10.49 seconds.
- Answer: 9.53 meters per second
Solve:
To three significant digits, determine in meters per second the increase in speed of a roller coaster at the bottom of a 75.0 meter drop, neglecting the effects of air resistance.
- Answer: 38.3 (meters per second)
(For this one, I also got 38.36, which should be rounded to 38.34)
I would have challenged that if it were counted wrong.
Solve:
Marcia flew her ultralight plane to a nearby town against a head wind of 15 kilometers per hour in 2 hours and 20 minutes. The return trip under the same wind conditions took 1 hour and 24 minutes.
Find the plane’s air speed in km/h.
- Answer: 60 km/hr
(This was a team question.)
Solve:
On Memorial Day weekend I drove the 112 miles from Cincinnati to Indianapolis in one hour and forty-two minutes. My average speed was [BLANK] to the nearest whole mile-per-hour which was considerably less than the cars participating in the Indy 500 at the Brick Yard.
(This was a team question.)
Answer: 66 mph
Solve:
To two significant digits, calculate in meters per second the speed of a free-falling object after 6.0 seconds assuming the object starts from rest.
- Answer: 59 (meters per second)
- final speed = acceleration * time
- vf = (9.81) * (6.0)
Solve:
Claudius has designed a waterfall as part of an aqueduct. The waterfall is 10 meters tall. Determine in meters per second, the speed of the water at the bottom of the waterfall.
- Answer: 14 meters per second
Solve:
I wonder to two significant digits what Alice’s landing speed would be in meters per second, if she fell down a rabbit hole that was 15 meters in depth. Assume she started from rest and there is no air resistance in the rabbit hole.
- Answer: 17 meters per second
Solve:
To one significant digit, calculate in meters per second the speed of a set of keys, just as they strike the ground, given that they are thrown downward with an initial speed of 3 meters per second from the top of a 20 meter parking garage.
- Answer: 20 meters per second
Solve:
Bill is standing at the top of a 50. meter tall building and throws a set of keys down to Ted with an initial speed of 1.5 meters per second. To two significant digits, determine in meters per second, the speed of the keys when they impact the ground.
- Answer: 31 meters per second
Solve:
To three significant digits, determine in meters the displacement of a ball that is launched upward with an initial velocity of 25.0 meters per second after the ball has been in flight for 3.75 seconds.
- Answer: 24.8 meters
Solve:
To two significant digits calculate in meters per second squared the acceleration of a car traveling due east that is uniformly decreasing its speed from 25 meters per second to 15 meters per second over a 9.5 second period of time.
- Answer: -1.1 meters per second squared (or 1.1 m/s^2 WEST.)
- Acceleration is the change in velocity over the change in time. Here, it’s -10 / 9.5. The direction is negative because the car is decelerating (or accelerating in the opposite direction.)
(If a direction is not included, you’ll be prompted for more information)
To two significant digits calculate in meters per second squared the average acceleration of an object traveling in a straight line given that the object start from rest at t equals zero and is traveling at a speed of 12 meters per second at t equals 6.5 seconds.
- Answer: 1.8 meters per second squared
- Acceleration is change in velocity over the change in time. The change in velocity is 12 m/s, the change in time is 6.5 seconds, therefore the answer is 12 / 6.5 = 1.8 meters per second squared.
Solve:
Aladdin is traveling on his “limo-sized” magic carpet at a constant speed of 15 m/s and is walking at a
speed of 1.0 m/s from the front of the carpet to the back of the carpet. At what speed in m/s is Aladdin
traveling relative to a stationary observer on the street?
- Answer: 14 m/s
- This is a vector addition problem. The carpet is traveling 15 m/s in the positive direction, Aladdin is traveling 1.0 m/s in the negative direction, therefore an observer sees the sum: 15 + (-1) = 14 m/s.
Solve:
To two significant digits, calculate in meters the distance a dropped object has fallen in 5.5 seconds. Neglect air resistance.
- Answer: 150 meters
Solve:
To two significant digits, determine in meters per second the final speed of an object thrown from a height of 75 meters given that the object’s initial velocity is - 7.5 meters per second.
- Answer: 39 meters per second
Solve:
To three significant digits, determine in meters the maximum height of a rocket launched from rest with an acceleration of 58.8 meters per second squared given that the acceleration lasts for 12.5 seconds and the rocket continues to coast.
- Answer: 32,200 meters
(GPT gets 32,100 meters.)
Solve:
To two significant digits, calculate in meters the minimum length of the runway necessary for an airplane needing to reach a speed of 75 meters per second for takeoff given the engines can exert a uniform acceleration of 2.5 meters per second squared.
- Answer: 1100 meters
Solve:
To two significant digits, determine the speed in meters per second of a 15.0 kg ball thrown straight down from a height of 2.5 meters, which strikes the floor with a speed of 9.0 meters per second.
(The question is asking for the inital velocity of the thrown ball.)
- Answer: 5.7 meters per second
Solve:
To two significant figures, calculate in meters, the maximum height reached by a 3.5 kg ball thrown upward at an initial velocity of 11.5 meters per second assuming no air resistance.
- Answer: 6.7 meters
- You can use conservation of energy here (set KE = PE, solve for h) or you can use the max height formula (Max height = (initial v squared) / (2 * grav)).
(Remember: Mass has no impact on kinematics if no air resistance)
Solve:
Arthur Dent threw himself toward the ground from a height of 16,700 meters. To two significant figures, determine in seconds the time it would have taken him to hit the ground had he not missed. Neglect initial velocity; acceleration of gravity is 18.93 meters per second squared.
(I don’t know anything about Hitchhiker’s Guide to the Galaxy or why we’re using a weird number for acceleration due to gravity.)
- Answer: 42 seconds
(Oh, I get it. 42 is the answer to everything. Or something. I haven’t read the book.)
Solve:
Thor throws his hammer vertically straight up with an initial velocity of 100. meters per second.
To two significant digits, determine in meters the maximum height reached by Thor’s hammer.
- Answer: 510 meters
- Seems like a great occasion to use the max height formula (max height = (initial velocity squared) / (2 * g ))
Solve:
To two significant digits, calculate in meters per second the speed at which Mario will hit the ground given that he falls from a platform 10. meters high and misses the steel girder parallel to the platform.
(Team Question)
- Answer: 14 meters per second
Solve:
To two significant digits calculate the magnitude of the average acceleration in meters per second squared of a car that is traveling at a speed of 15 meters per second and then increases its speed to 35 meters per second in 22 seconds.
- Answer: 0.91 m/s^2
- Average acceleration is the change in velocity over the change in time. Here, that means (20 m/s) / (22 s).
(Note: Answer key says “do not accept a negative answer”)
Solve:
A projectile is shot straight up into the air with an initial speed of 25 meters per second.
To two significant digits determine in seconds the time it takes the projectile to reach its maximum height.
- Answer: 2.6 seconds
(The answer key says 32 seconds. There’s no way.)
Solve:
To two significant digits, calculate in meters the range of a projectile fired horizontally at a speed of 55 meters per second from a 120-meter-tall hill.
- Answer: 270 meters per second
Isaac drops an apple from the top of a 65-meter-tall tower. To two significant digits, determine in meters per second the speed of the apple when it reaches the ground given that the apple starts from rest.
- Answer: 36 meters per second
Solve:
For the next question you will need this information. A train is traveling North at a constant speed of 2.0 meters per second when it begins to accelerate at a rate of 0.80 meters per second squared. At the same time the train begins to accelerate, a ticket collector drops a coin which takes one-half of a second to hit the floor. Neglect friction.
Complete the following statement using one of the four given choices. Relative to a spot on the floor directly beneath the point where the coin was released, the coin will land …
Choice 1: 1.6 meters toward the rear of the train.
Choice 2: directly on the spot.
Choice 3: 0.10 meters toward the rear of the train.
Choice 4: 0 .90 meters toward the rear of the train.
- Answer: Choice 3, 0.10 meters toward the rear of the train.
- The question is essentially asking how far the train moved if it accelerated forward at 0.80 meters per second squared for half a second.
To two significant digits, calculate in meters the minimum length of the runway necessary for an airplane needing to reach a speed of 75 meters per second for takeoff given the engines can exert a uniform acceleration of 2.5 meters per second squared.
Solve:
To two significant digits, calculate in meters per second, the final velocity of a vehicle that uniformly accelerates from rest at 1.8 meters per second squared over a displacement of 75 m.
- Answer: 16 meters per second
Solve:
You cross a stream from west to east at a point where it is 10 meters wide and is flowing south at a rate of 3 meters per second. Your boat can travel 4 meters per second in still water.
This is a three-part question. Determine the following needed for the trip:
1. the speed in meters per second as seen by an observer on the shore
2. the resulting angle to the neatest degree of travel measured clockwise from due North
3. the time in seconds
(This is a weird one from 1996.)
- Part 1 Answer: 5 meters per second
- Part 2 Answer: 127 degrees
- Part 3 Answer: 2.5 seconds
Solve:
To two significant digits calculate in meters per second the speed of an object on a planet where the acceleration due to gravity is 15 meters per second squared after the object has been in freefall for 3.0 seconds.
- Answer: 45 m/s
- This one is straightforward. If the speed increases by 15 m/s per second for three seconds, the final speed is 45 m/s.
Solve:
To three significant digits, determine the speed in meters per second of Dilbert’s computer as it impacts his boss’s car when dropped from a height of 30.0 meters.
- Answer: 24.2
Solve:
A cat on top of a refrigerator rolls off and lands on the floor with a speed of 6.2 meters per second. To
the nearest tenth, calculate in meters, the height of the refrigerator.
- Answer: 2.0 meters
Solve:
A cannon ball is projected towards a cliff with an initial speed of 42 meters per second at an angle of 60. degrees above the horizontal.
To two significant digits, calculate in meters the
height of the cliff given that the cannon ball lands on the top of the cliff 5.5 seconds after being fired
- Answer: 52 meters
Solve:
To two significant digits, calculate in seconds the amount of time it would take a projectile to impact the ground given that it is thrown downward with an initial velocity of 10. meters per second from a height of 50. meters.
- Answer: 2.3 seconds
Solve:
To three significant digits, determine in seconds the time it takes for an object thrown down from a height of 75.0 meters at an initial velocity of 15.0 meters per second to hit the ground. Neglect air resistance.
- Answer: 2.67 seconds
(This is a weird one requiring the quadratic equation.)
Solve:
Solve:
A 5.0-kilogram ball is dropped from a height of 45 meters. To two significant digits calculate in meters per second the speed of the ball as it just strikes the ground.
- Answer: 30 meters per second
Solve:
Galileo dropped a wooden sphere from the Leaning Tower of Pisa at a height of 55 meters.
To two significant digits, calculate in seconds the time it took the sphere to reach the ground. Ignore air resistance.
- Answer: 3.4 seconds
Solve:
The CN Tower in Toronto stands at a height of 553 meters. The Burj Dubai skyscraper will reach a height of 800. meters.
If a penny is dropped from the top of each structure, to two significant digits, calculate in meters per second the difference in the speed of the pennies just as they hit the ground after falling.
- Answer: 21 meters per second
Solve:
A 1.3-kilogram watermelon is dropped from a 25-meter high cliff at the same time a person at the bottom of the cliff shoots an arrow straight towards the watermelon from a height of 2.0 meters above the ground. The arrow strikes the watermelon 0.35 seconds later.
To two significant digits calculate in meters the height above the ground at which the arrow strikes the watermelon.
- Answer: 24 meters
Solve:
To two significant digits calculate in meters the height of the center of a target 59 meters from an archer who accurately shoots an arrow at an angle of 35 degrees at an initial velocity of 25 meters per second from a height of 1.5 meters.
- Answer: 2.1 meters
Solve:
Tom Brady throws a football horizontally with an initial speed of 25 meters per second from a height of 10. meters.
To two significant figures, calculate in meters the distance the ball traveled in the air. Neglect air resistance.
- Answer: 36 meters
(They should have specifically asked for the horizontal distance.)
Solve:
To two significant digits, determine in meters the distance an object falls under the influence of gravity given that the initial velocity of the body is 5. 0 meters per second and the final velocity is 90. meters per second. Assume no air resistance.
- Answer: 410 meters
Solve:
To one significant digit, determine in meters the distance from a 70 meter tall vertical cliff a rock would land given that the rock is thrown horizontally at an initial speed of 15 meters per second.
- Answer: 60 meters
Solve:
To one significant digit, determine in kilometers the distance from the separation point that an autonomous drone ship must be placed in order to recover a Falcon 9 first stage, given that the stage separates at an altitude of 80 kilometers with a speed of 2100 meters per second at an angle of 53 degrees above the horizontal. Assume the drone ship is located on the surface of the Earth and neglect air resistance.
(They should have clarified this: The “Falcon 9 First Stage” is part of a reusable SpaceX rocket that falls back to Earth and is recovered by a self-piloting ‘drone ship’ boat on Earth.)
- Answer: 500 meters
Solve:
To two significant digits, calculate in meters per second squared the acceleration of a car that starts from rest and travels a distance of 150 meters over a time interval of 4.7 seconds.
- Answer: 14 meters per second squared
Solve:
Given that sound in air is traveling one kilometer every three seconds, to three significant digits calculate in meters the distance of a storm when the difference between a flash of lightning and a clap of thunder is 2 seconds.
- Answer: 667 meters
Solve:
To two significant digits, calculate in meters per second the initial speed of a wolverine that leaps a horizontal distance of 73 meters at an angle of 45°. Neglect air resistance.
- Answer: 27 meters per second
Solve:
A cyclist passes a checkpoint at a speed of 4.7 meters per second. As he passes the checkpoint, he begins to slow down at a rate of 0.25 meters per second squared.
To two significant digits state the distance in meters the cyclist will have traveled upon coming to rest.
- Answer: 44 meters
Solve:
To two significant digits calculate in meters the distance required for a roller coaster car to come to rest when it is initially traveling at 12.5 meters per second and begins to uniformly accelerate at a rate of -6.5 meters per second squared.
- Answer: 12 meters
Solve:
To three significant digits, determine in meters per second squared the acceleration of a car starting from rest that accelerates to 25.0 meters per second over a distance of 75.0 meters.
- Answer: 4.17 meters per seconds squared
To three significant digits, determine the distance in meters between two grocery store bag boys who are rolling a certain pickle jar starting from rest with an acceleration of .500 meters per second squared down a grocery aisle given that it takes 5.00 seconds for the jar to travel from one bag boy to the other.
- Answer: 6.25 meters
Solve:
At a recent regatta in California, The San Diego Crew Classic, results from the Men’s Cal-Visitor’s Cup Grand Final with their times were as follows:
- Oregon State University 6:17.12
- U.C. San Diego 6:24.55
- Columbia University 6:25.71
- U.C. Irvine 6:27.37
- Wichita State University 6:30.34
- U.C. Santa Barbara 6:31.56
To two significant digits calculate in meters the distance U.C. Irvine finished behind Oregon State University if the course was 2000. meters long. Assume constant velocity for all boats.
(This was a handout question.)
- Answer: 53 meters
(Note: GPT arrived at 54 meters for its answer.)
Forces
Identify the quantity that a spring scale measures and its units.
Answer: A spring scale measures force in Newtons.
Which one or ones of the following four have the unit of force?
1. friction
2. coefficient of friction
3. weight
4. mass
Answers: 1 and 3 (friction and weight)
In physics, what is represented by the lowercase Greek letter, mu?
Answer: Coefficient of Friction
0.
Which one of the following four could not produce equilibrium with a 4 Newton force and a 12 Newton force acting concurrently on a point?
- 6 Newtons
- 16 Newtons
- 10 Newtons
- 8 Newtons
Answer: 1. 6 Newtons
A 1000-kilogram automobile accelerates from rest to 20 meters per second in 5 seconds. Calculate the force in newtons which the road exerts on the car in order to cause this acceleration.
Answer: 4000 Newtons
To two significant digits, determine in meters per second squared the acceleration of a Cessna 172 given that the engine’s propeller produces a thrust of 1,700 Newtons, drag is 1,200 Newtons, and the aircraft has a mass of 1,043 kilograms.
Answer: 0.48 meters per seconds squared
Donald and Goofy are arguing over a CAC lanyard that has a mass of 2.5 kilograms attached to it. Donald pulls to the left on the lanyard with a horizontal force of 25 Newtons, and Goofy pulls on it to the right with a horizontal force of 28 Newtons. To two significant digits, calculate in meters per second squared the magnitude of acceleration of the mass.
Answer: 1.2 (meters per second squared)
To two significant digits, determine in newtons the force that causes a 1,200 kilogram automobile to accelerate from 5.0 meters per second to 15 meters per second in 7.0 seconds.
Answer: 1700 Newtons
To two significant digits, calculate the acceleration in meters per second squared of a 25 kilogram crate, initially at rest, given that a 1,200 newton force is applied. Assume no friction.
Answer: 48 meters per second squared
To two significant digits calculate in newtons the magnitude of the normal force acting. on a 102-kilogram block resting on a 32-degree inclined plane.
Answer: 850 Newtons
The coefficient of friction between a 10.0-kilogram block and an inclined plane is 0.700 If the angle of the plane is increased slowly, then calculate to two significant digits the
degree measure of the angle at which the box will just begin to slide.
Answer: 35 degrees
To three significant digits, determine in meters per second squared the acceleration of a 10.0 kilogram mass up a plane inclined at an angle of 37.0 degrees given that mass 1 is pulled via an ideal string over an ideal pulley that is connected to a 15.0 Kg mass hanging vertically from the pulley. Assume the coefficient of friction is 0.350.
Answer: 2.43 meters per second squared
To three significant digits, determine the coefficient of static friction for a block that rests on an inclined plane given that the plane is at an angle of 53.0°.
Answer: 1.33
To two significant digits, determine in meters per second squared the acceleration of a 15 kilogram box moved by a 120 Newton force across a surface whose coefficient of friction is 0.65.
Answer: 1.6 meters per second squared
To two significant digits, determine the minimum coefficient of static friction between a 25 kilogram box and the surface of a ramp with an angle of inclination of 37°.
Answer: 0.75
To three significant digits, calculate the coefficient of static friction of an object just before it begins to slide down a ramp inclined at 37.0 degrees.
Answer: 0.754
To three significant digits, determine in meters per second squared the acceleration of a 2.50 kilogram wood block down a ramp that is inclined at 37.0° with respect to the horizontal and coefficient of friction of 0.155.
Answer: 4.68 meters per second squared
To two significant digits, calculate in meters per second squared the acceleration of a 25- kilogram box that is sliding down a ramp that is inclined at 53 degrees with respect to the horizontal. The coefficient of friction is 0.37.
Answer: 5.6 meters per second squared
To two significant digits, determine in meters per second squared the acceleration of a 30 kilogram block down a ramp having a coefficient of kinetic friction of 0.20 and making an angle of 25 degrees with respect to the horizontal.
Answer: 2.4 meters per second squared
To one significant digit, determine in meters per second squared the magnitude of acceleration for a skier skiing down a 30 degree slope with respect to the horizontal. Assume the slope is frictionless.
Answer: 5 meters per second squared
To three significant digits, determine the coefficient of kinetic friction for a 45.0 kilogram box on a level surface when a 200. Newton constant force is applied.
Answer: 0.454
To two significant digits calculate the coefficient of static friction between a 2.6-kilogram block and an incline if the maximum angle of the incline just before the block slips is 28 degrees with the horizontal.
Answer: 0.53
What is the largest possible resultant force, in newtons, of two concurrent forces with magnitudes of 2 newtons and 5 newtons?
Answer: 7 Newtons
Give the magnitude of two concurrent forces that have a maximum resultant of 235 newtons and a minimum resultant of 5.00 newtons.
Answer: 120 and 115 Newtons
To two significant digits, determine in Newtons the weight of a 15 kilogram object.
Answer: 150 Newtons
If Tara has a mass of 50 kilograms, to one significant digit, determine her weight in Newtons
Answer: 500 Newtons
The combined mass of the twin solid rocket boosters on the Artemis 1 rocket is 3.2 million kilograms. To two significant figures, calculate in Newtons the weight of the boosters.
Answer: 31,000,000 (or 3.1 x 10^7) Newtons
To two significant digits, determine in kilograms the mass of an object if an applied force of 25 Newtons produces an acceleration of 1.2 meters per second squared.
Answer: 21 kilograms
A Ford Mustang has a mass of 1800 kilograms. Given that the Mustang requires an applied force of 3100 newtons to accelerate, to two significant digits, determine in meters per second squared the magnitude of the acceleration.
Answer: 1.7 meters per second squared
To two significant digits, determine in kilograms the mass of a truck given that an applied force of 2500 Newtons is required to accelerate the truck at 0.65 meters per second squared.
Answer: 3800 kilograms
Bill and Ted are each pulling on a 3-kilogram box of nachos. Bill pulls to the left with a force of 60 newtons and Ted pulls to the right with a force of 75 newtons.
To one significant digit, determine in meters per second squared the magnitude of the acceleration of the box of nachos.
Answer: 5 meters per second squared
A 12-kilogram box is pulled across the floor with a horizontal force of 55 newtons. Given that the frictional force is 14 newtons, to two significant figures, calculate in meters per second squared the magnitude of the acceleration of the box.
Answer: 3.5 meters per second squared
A 25-kilogram box is pulled across the floor with a horizontal force of 65 newtons. Given that the frictional force is 12 newtons, to two significant figures, calculate in meters per second squared the magnitude of the acceleration of the box.
Answer: 2.1 meters per second squared
Gene and Howard are each pulling on a 1.5-kilogram rope during a tug-of-war competition. Gene pulls to the left with a force of 67 newtons and Howard pulls to the right with a force 66 newtons. To two significant figures, calculate in meters per second squared the magnitude of the acceleration of the rope.
Answer: 0.67 meters per second squared
To three significant digits calculate in newtons the apparent weight of a woman with a mass of 45.0 kg standing on a scale in an ascending elevator accelerating at the rate of 2.50 meters per second.
Answer: 554 (Newtons)
To two significant digits, determine in Newtons the weight as indicated by a scale for a 55 kilogram person who is descending in one of the Contemporary’s elevators, given that the elevator is descending at 0.15 meters per second squared.
Answer: 530 Newtons
To two significant digits calculate respectively in newtons the vertical and horizontal components of a 75-newton force acting at an angle of 45 degrees.
Answer: 53 and 53 Newtons
A 739 kilogtam smart car travels with an initial velocity of 15 meters per second. The car takes 5.0 seconds to come to rest. To two significant digits, determine in Newtons the magnitude of the braking force.
Answer: 2,200 Newtons
To two significant digits, determine in Newtons the tension in the string of an ideal Atwood machine given that mass 1 is 15 kilograms and mass 2 is 12 kilograms. Assume the string is massless and extensionless, and the pulley is frictionless.
Answer 130 Newtons
To two significant digits, determine in meters per second squared the magnitude of the acceleration produced by two masses on an ideal Atwood machine given that mass 1 is 15 kilograms and mass 2 is 18 kilograms. Assume the string is massless and extensionless, and the pulley is frictionless.
Answer: 0.89 meters per second squared
To two significant digits, calculate in meters per second squared the magnitude of the acceleration of a 1.01-kilogram mass attached to a 0.99-kilogram mass by a massless string on an Atwood machine. Neglect friction and assume the pulley is massless.
Answer: 0.098 meters per second squared
The engine of a certain boat exerts a 415-newton force in the northward direction while the wind is pushing on the boat with a force of 325 newtons in the westerly direction. The current exerts a force of 250 newtons in the southerly direction.
To two significant digits calculate respectively in newtons and degrees the magnitude and direction of the resultant force relative to the positive x-axis acting on the boat.
Answer: 360 and 150 Newtons
To three significant digits, determine in meters per second squared the magnitude of acceleration of an object that has a mass of 25.0 kg if a force of 100. Newtons is required to move it.
Answer: 4.00 meters per second squared
Which one or ones of the following four statements are correct concerning Newton’s First Law?
1. explains the resistance to any change in motion
2. explains, in part, centrifugal force
3. also known as the law of inertia
4. plays a role in the conservation of angular momentum
Answer: All four are correct.
Which one of the following four is a measure of the inertia of a moving object?
1. mass
2. momentum
3. power
4. energy
Answer: 1. Mass
This refers to an upward force caused by displacement of a fluid
Buoyant Force
Solve:
A boat displaces 6.7 x 10^8 Newtons of fresh water when floating. To two significant digits, calculate in cubic meters the difference in volume of water displaced if the boat is now placed in salt water, where the density of salt water is 1020 kilograms per meter cubed. The density of freshwater is 998 kilograms per meter cubed.
- Answer: 1500 cubic meters
Solve:
To two significant digits, determine the coefficient of sliding friction between the blades of an 81 Newton sled that is pulled across a driveway at constant speed with a 38 Newton force exerted on the handle causing an angle of 42 degrees with the ground.
- Answer: 0.51
To two significant digits calculate the coefficient of friction for a 20-kilogram mass being pulled along a level surface at a constant velocity of 3 .2 meters per second by a horizontal force of 130 newtons.
Answer: 0.66
A 15 kg block is being pulled with a 18 Newton force across a horizontal surface at constant velocity. To two significant digits, calculate the coefficient of sliding friction between the block and the ground.
Answer: 0.12
To two significant digits calculate the coefficient of friction between a 75-kilogram box and the floor if the box is being pulled across the floor with a constant 120-newton force at
an angle of35 degrees to the horizontal.
Answer: 0.15
To two significant digits calculate in meters per second squared the constant acceleration of the block if the coefficient of kinetic friction between the block and the
horizontal surface is 0.15.
Answer: 1.5 meters per second
To two significant digits, determine in meters per second squared the acceleration of a 15 kilogram box moved by a 120 Newton force across a surface whose coefficient of friction is 0.65.
Answer: 1.6 meters per second squared
Solve:
To two significant digits, calculate the coefficient of friction between a horizontal surface and a 25 kilogram box sliding at a constant speed due to an applied horizontal force of 75 Newtons.
- Answer: 0.31
Solve:
A small child pulls a 25 kilogram toboggan across a flat surface with a horizontal force of 75 Newtons at a constant speed. To one significant digit, determine the coefficient of kinetic friction between the toboggan and the flat surface.
- Answer: 0.3
Solve:
To two significant digits determine the coefficient of kinetic friction of a 25 kg object on a horizontal surface given that the object is dragged across the surface at a constant speed by a 75-newton force.
- Answer: 0.31
A Tesla Roadster has a mass of 1300 kilograms and a magnitude of acceleration of 13.8 meters per second squared. To two significant digits, calculate in Newtons the force applied to the Tesla.
- Answer: 18,000 Newtons
A Tesla Model X has a mass of 2300 kilograms and a magnitude of acceleration of 24.6 meters per second squared. To two significant digits, calculate in Newtons the force applied to the Tesla.
Answer: 57,000 Newtons
Circular Motion
Provide the formula for:
Calculating the centripetal force
(for an object moving in a circle.)
Centripetal Force = [(mass) * (velocity squared)] / (radius)
Fc is in Newtons, m in kilograms, v in meters/sec, r in meters
Calculating centripetal acceleration
Memorize this:
Give the value for G, the gravitational constant to three significant figures.
Calculating minimum velocity required for orbit
(This is called the critical speed.)
For an object in uniform circular motion, the centripetal force is in this direction.
Towards the center of the circle