Physics 1 Final Flashcards
If an object is accelerating toward a point, then it must be getting closer and closer to that point.
True
False
False
Two objects are thrown from the top of a tall building and experience no appreciable air resistance. One is thrown up, and the other is thrown down, both with the same initial speed. What are their speeds when they hit the street?
- The one thrown down is traveling faster.
- They are traveling at the same speed.
- The one thrown up is traveling faster.
They are traveling at the same speed
A pilot drops a bomb from a plane flying horizontally at a constant speed. Neglecting air resistance, when the bomb hits the ground the horizontal location of the plane will
- depend of the speed of the plane when the bomb was released.
- depend of the mass of the bomb when it was released.
- be in front of the bomb.
- be over the bomb.
- be behind the bomb.
be over the bomb
What type of acceleration does an object moving with constant speed in a circular path experience?
- free fall.
- linear acceleration.
- constant acceleration.
- terminal acceleration.
- centripetal acceleration.
centripetal acceleration
Suppose that a car traveling to the west (the -x direction) begins to slow down as it approaches a traffic light. Which statement concerning its acceleration in the x direction is correct?
- Both its acceleration and its velocity are positive.
- Both its acceleration and its velocity are negative.
- Its acceleration is negative but its velocity is positive.
- Its acceleration is positive but its velocity is negative.
Its acceleration is positive but its velocity is negative.
If the graph of the position as a function of time for an object is a horizontal line, that object cannot be accelerating.
- True
- False
True
If the acceleration of an object is negative, the object must be slowing down.
- True
- False
False
The magnitude of a unit vector is one.
- True
- False
True
An object is moving with constant non-zero acceleration along the +x-axis. A graph of the velocity in the x direction as a function of time for this object is
- a horizontal straight line.
- a straight line making an angle with the time axis.
- a parabolic curve.
- a vertical straight line.
a parabolic curve
A man walks south at a speed of 2.00 m/s for 15.0 minutes. He then turns around and walks north a distance 2000 m in 15.0 minutes. What is the average speed of the man during his entire motion?
Average speed = Total distance/elapsed time
Since you are given velocity and time instead of initial distance, you must use the velocity formula to find the distance. v= x/t, manipulate the formula to give you x= vt. This will give you the initial distance.
Convert the time from minutes to seconds
Then enter all information into the average speed formula.
A hockey puck slides off the edge of a table with an initial velocity of 20.0 m/s. The height of the table above the ground is 2.0 m. What is the magnitude of the velocity of the puck just before it touches the ground?
Given: initial velocity=20.0m/s, initial height=2.0m, final height= 0m (since it hit the ground), gravity= -9.8m/s^2
Find: Magnitude of the final velocity before it hits the ground.
Since this is a free fall problem you can use free fall kinematic formula.
Best formula to solve for final velocity with the information given is v^2=vi^2-2g(y-y0)
A projectile is launched from ground level at an angle of 30.0° above horizontal with a speed of 10.0 m/s. If the projectile is moving over level ground, what is the maximum height above the ground that the projectile reaches?
To find maximum height use formula: hmax= (v0sin(angle))^2/2g
A girl attaches a rock to a string, which she then swings counter-clockwise in a horizontal circle. The string breaks at point P in the figure, which shows a bird’s-eye view (as seen from above). Which path (A-E) will the rock follow?
Path B
You are standing in a moving bus, facing forward, when you suddenly slide forward as the bus comes to an immediate stop. What force caused you to slide forward?
- gravity
- the force due to friction between you and the floor of the bus
- There is not a force causing you to slide forward.
- the normal force due to your contact with the floor of the bus
There is not a force causing you to slide forward
You push on box G that is next to box H, causing both boxes to slide along the floor, as shown in the figure. The reaction force to your push is
- the upward force of the floor n box G.
- the acceleration of box G.
- the push of box G against you.
- the push of box H on box G.
- the push of box G on box H.
The push of box G against you
When a car goes around a circular curve on a horizontal road at constant speed, what force causes it to follow the circular path?
- the friction force from the road
- the normal force from the road
- gravity
- No force causes the car to do this because the car is traveling at constant speed and therefore has no acceleration.
the friction force from the road
If the rockets of a spaceship in outer space (far from all gravity) suddenly lose power and go off, the spaceship will gradually slow to a stop.
True
False
False
What is the mass of an object that experiences a gravitational force of 603 N near Earth’s surface where g = 9.80 m/s2?
Given: force = 603N, g = 9.8 m/s2
Find: m =?
Use Newtons second law equation F = ma. Rearrange equation to solve for m = F/g.
A driver in a 1000-kg car traveling at 19 m/s slams on the brakes and skids to a stop. If the coefficient of friction between the tires and the level road is 0.80, how long will the skid marks be?
Draw a free body diagram and identify forces. ( Fgravity, Normal force, force of friction)
Given: mass of car = 1000kg, initial velocity = 19m/s, final velocity = 0, coefficient of friction = 0.80.
Find: Displacement.
Formula to use:
F=ma to solve for acceleration
vf^2 = vi^2 + 2ad to solve for displacement
Pulling out of a dive, the pilot of an airplane guides his plane into a vertical circle with a radius of 600 m. At the bottom of the dive, the speed of the airplane is 150 m/s. What is the apparent weight of the 70-kg pilot at that point?
In a carnival ride, passengers stand with their backs against the wall of a cylinder. The cylinder is set into rotation and the floor is lowered away from the passengers, but they remain stuck against the wall of the cylinder. For a cylinder with a 2.0-m radius, what is the minimum speed that the passengers can have so they do not fall if the coefficient of static friction between the passengers and the wall is 0.25?
The figure illustrates a uniform metal sheet shaped like a triangle, with a hole cut in the center. Where is the center of mass of this object, relative to the coordinate system shown?
- Somewhere on the y-axis, where x = 0.
- Somewhere on the x-axis, where y = 0.
- The center of mass has non-zero a and y components.
- None of these - you need to add up each little mass of the triangle to find the answer.
Somewhere on the y-axis, where x=0
Consider a bike wheel that is hanging from a rope tied to one end of its axle. If you get the bike wheel spinning quickly about its axis and let it go, what direction will it move?
- Horizontally, with its own axis coinciding with the rope
- It will not move at all
- Upwards
- Around the vertical axis that coincides with the rope.
- Downwards
Around the vertical axis that coincides with the rope.
Consider the ball shown in the figure, moving in a circle. What is the direction of the angular momentum of the ball?
- Angular momentum does not have a direction
- In the same direction as its motion - around the circle, in the angular
direction - In the horizontal direction (sideways)
- In the same direction as its motion - tangential to the circle
- In the vertical direction (upwards)
- Out of the page
Out of the page
Three objects are connected by weightless flexible strings as shown in the figure. The pulley has no appreciable mass or friction, and the string connected to the block on the horizontal bench pulls on it parallel to the bench surface. The coefficients of friction between the bench and the block on it are µs = 0.66 and µk = 0.325. You observe that this system remains at rest.
(a) Find the mass of the hanging object A.
(b) What is the magnitude of the friction force on the block on the bench?
Draw free body diagram for all 3 objects
Sum of Forces
Find mass
Find friction
The figure shows a block of mass m resting on a 20° slope. The block has coefficients of friction μs = 0.65 and μk = 0.55 with the surface of the slope. It is connected using a very light string over an ideal pulley to a hanging block of mass 2.0 kg. The string above the slope pulls parallel to the surface. What is the minimum mass m so the system will remain at rest when it is released from rest?
Draw free body diagram
Sum of forces in x and y direction
Since no acceleration due to system being at rest the sum of forces equal 0
Substitute T with m2g and solve for m1.
A 600-kg car is going around a banked curve with a radius of 110 m at a steady speed of 18.5 m/s. What is the appropriate banking angle so that the car stays on its path without the assistance of friction?
The curved section of a horizontal highway is a circular unbanked arc of radius 160 m. If the coefficient of static friction between this roadway and typical tires is 0.40, what would be the maximum safe driving speed for this horizontal curved section of highway?
The figure shows a system consisting of three blocks, a light frictionless pulley, and light connecting ropes that act horizontally on the upper two blocks. The 9.0-kg block is on a perfectly smooth horizontal table. The surfaces of the 12-kg block are rough, with µk = 0.30 between the 12-kg and 9.0-kg blocks. The mass M of the hanging block is set so that it descends at a constant velocity of 3.25 m/s.
(a) What is the mass M of the hanging block?
(b) The mass M is now changed to 5.0 kg, causing it to accelerate downward after it is released. What is the acceleration of the hanging mass?
A 2 kg block situated on a frictionless incline is connected to a light spring (k = 100 N/m). The block is released from rest when the spring is unstretched. The pulley is frictionless and has negligible mass. What is the speed of the block when it has moved 0.2 m down the plane?
Use Conservation of Energy formula to solve this problem
The only force acting on a 2 kg body as it moves out the positive x-axis is given by F = -(6x) N, where x is in meters. If the kinetic energy of the body at x = 2 m is 60 J, what is its kinetic energy at x = 3 m?
Use Work integral formula
Then use Conservation of energy formula
A 2.4 kg ball falling vertically hits the floor with a speed of 2.5 m/s and rebounds with a speed of 1.5 m/s. What is the magnitude of the impulse exerted on the ball by the floor?
Impulse formula–> delta P= m(vf-vi)
A 10 g bullet moving 1000 m/s strikes and passes through a 2 kg block initially at rest. The bullet emerges from the block with a speed of 400 m/s. To what maximum height will the block rise above its initial position?
Use Conservation of Momentum to find velocity
Then use kinematic equation to find height
Three particles are placed in the x-y plane. A 40 g particle is located at (4,3) meters, and a 50 g particle is located at (-2, 2) meters, where must a 20 g particle be placed so that the center of mass of the three particle system is at the origin?
Use center of mass formula
A 1.5 kg block resting on a horizontal frictionless surface has a hole bored into it in a 0.5 kg ideal spring is placed. A 500 g ball is fired into a hole at a speed of 50 m/s. The spring subsequently is compressed a distance of 6 cm, at which point a ratchet mechanism locks the spring into place. The block and ball move off together at a speed v’.
a) Calculate v’.
b) Calculate the kinetic energy decrease of the system as a result of the collision.
c) How much of that energy is stored in the spring as potential energy if k = 100,000 N/m?
Two particles (m1 = 0.2 kg, m2 = 0.3 kg) are positioned at the ends of a 2 meter long rod of negligible mass. What is the moment of inertia of this rigid body about an axis perpendicular to the rod and trough the center of mass.
Planet Roton has a mass of 4 X 1023 kg and a radius of 2 X 106 m. With what speed should a space probe be launched from the surface of Roton so as to achieve a maximum distance of 3 X 106 m from the center of the Roton? (G = 6.67 X 10-11 N-m2/kg2)
The period of a satellite circling planet Nutron is observed to be 84 seconds when it is in a circular orbit with a radius of 8 X 106 m. What is the mass of planet Nutron? (G = 6.67 X 10-11 N-m2/kg2)
A uniform, horizontal beam (length = 10 m, mass = 25 kg) is pivoted at the wall, with its far end supported by a cable that makes an angle of 50 degrees with the horizontal. If a person (mass = 60 kg) stands 3 meters from the pivot, what is the tension in the cable?
A turntable of a record player has an angular velocity of 8 rad/s when it is turned off. The turntable comes to rest 2.5 seconds after being turned off. Through how many radians does the turntable rotate after being turned off? assume constant angular acceleration.
A particle of mass m = 100 g and speed v = 5 m/s collides and sticks to the end of a uniform solid cylinder of mass M = 1 kg and radius R = 20 cm. If the cylinder is initially at rest and is pivoted about a frictionless axle through its center, what is the final angular velocity (in rad/s) of the system after the collision?
