CH 2, 3, 4 and 5 mixed Flashcards
A plane traveling north at 300 km/h airspeed hits southerly wind of 300 km/h. What is landspeed?
- It will look like it is standing still in mid-air
what are the angle measures of a 1-1-root 2 triangle?
45 -45- 90 across from those sides respectively)
How is velocity different from speed?
50 m/s is a speed. 50 m/s NORTH is a velocity. Velocity is speed with direction.
If you are given a force and a mass, you can find ____ by using the equation ____
a = F/m
A plane traveling north at 300 km/h airspeed hits southerly wind of 50 km/h. What is landspeed?
250 km/h
When a bullet leaves a gun, explain why the bullet moves faster forward than the gun moves backward
bullet has small mass, lots of accelertion, gun has lots of mass, little acceleration
What is acceleration when 12N is applied to 3kg object? Why?
4 m/s2
If you have weight, how do you find directional force?
w*sin(angle) gives the directional force
Which is more stable, mass or weight? Explain
mass is same on earth or moon, weight changes
Discuss the vertical component of a thrown baseball
The vertical component is impacted by gravity, so always changing by 10m/s per second.
Suppose you know the hypotenuse and the measure of an angle, and want to find the side across from the angle, on the opposite side?
hypotenuse x SIN (angle) [sin finds opposite side]
What is Newton’s First Law?
Object stays at rest, or moves at a constant velocity in a straight line unless a force acts on it.
A plane traveling north at 300 km/h airspeed hits northerly wind of 50 km/h. What is landspeed?
350 km/h. The wind speed adds to groundspeed
What are the side lengths of the 45-45-90 triangle?
1, 1 and sqrt 2
When have you felt acceleration?
In a car when you speed up (pulled back), slow down (pulled forward) or turn (pulled away from turn direction).
About how fast do people run in m/s? (mph?) [km/h?]
4-6 m/s (9 - 15 mph) [ 15- 20 km/h]
a newton divided by acceleration (m/s2) will give you
mass (kg)
How much does a 3kg object weigh?
about 30N
If you drop a ball from rest, how far did it go after 1s ? 2s ? 5s?
distance is always “avg velocity times time” From rest we can say “distance = 5t2” So, 5m, 20m, 125m
SATELLITES: If an object falls at about 5 m in first second, and the earth curves about 5m every 8km. How fast would something have to travel horizontally to never hit the earth?
8km/s (neglecting air resistance)… now you orbit :)
SATELLITES: How many times does the international space station orbit the earth each day?
It circles the earth every 90 minutes, about 16 times a day!!
What are the side lengths of the 30-60-90 triangle?
1, sqrt 3 and 2
About how fast do people walk in m/s? (mph?) [km/h?]
1-2 m/s (2-5mph) [3-6km/h]
How can we add two vectors (find resultant) by sketching?
Use the parallelogram rule, and the DIAGONAL is the resultant vector when both components start from the same spot.
Give a quick summary of Newton’s three laws of motion:
FIRST: objects in motion or rest stay that way, SECOND: a = F/m , THIRD: action have equal opposite reactions
How do we make sure our calculator is in the right mode?
press MODE> put cursor on DEGREES> press ENTER
How can you think about the horizontal and vertical speeds of a projectile? (shadows)
For Vx, the horizontal, imagine the sun straight above and visualize the speed of the shadow cast on the ground. the speed of the shadow is the horizontal speed. For Vy, the vertical speed, imagine a huge spotlight behind where the projectile is being launched from, pointing in the direction of the projectiles path. Also imagine a wall just beyond it. the speed of the shadow of the ball on that wall is the vertical speed.
What is difference between vector and scalar quantities?
Vectors have magnitude and direction, so combining them is tricky. Scalars have magnitude only, so they can be easily added, subtracted, multiplied and divided.
a mass (kg) multiplied by an acceleration (m/s2) will give you
a newton (force)
Give examples of scalar quantities.
mass, time, volume, area.
Suppose you know the hypotenuse and the measure of an angle, and want to find the side close to the angle, how do you do it? how do you find the close side?
hypotenuse x COS (angle) [cosine finds the close side]
What did Galileo discover from ramps and marbles?
That the distance an object travels, due to gravity, is directly related to the SQUARE of the time it travels.
What is the difference between mass and weight?
mass is the amount of stuff, weight is the force on the planet it is on
How fast is the fasted human in m/s? (mph?) [km/h?]
over 10 m/s ! (25 mph +) [35 km/h +]
Explain why a projectile is traveling slowest at the top
We know the horizontal component is always the same, so that will always be contributing, but the vertical component becomes ZERO at the top. You can visualize this by imagining a ball thrown straight up.. it stalls at the top for a split second.
If you drop a ball from rest, what is avg speed after 1s ? 2s ? 5s?
avg speed = (start speed + end speed) / 2 From rest we can simply say “avg speed= 5 t” So…. 5m/s, 10m/s and 25 m/s
What is an interesting fact about horizontal ranges and angles (when kicking a soccer ball or firing an arrow?)
Complementary angles (angles that add to 90) have the same horizontal range. EXAMPLE: kicking a ball at 30 degrees will go the same distance as 60 degrees (neglecting air resistance. Shooting an arrow at 10 degrees will travel the same horizontal distance as one shot up at 80 degrees!!!
What has to be happening in order for net force to not be zero?
it must be ACCELERATING (changing velocity). just moving is not enough, it has to be changing speeds!
How fast do cars travel in m/s? (mph?) [km/h?]
15 m/s backroad, 30 m/s on highway (35 mph and 70 mph) [50-100 km/h]
If you throw a ball up at 80m/s, how long till it reaches the top?
8 seconds
If you are driving at 40 km/h and speed up to 60 km/h over 10 seconds, what was your acceleration?
Your speed changed 20 km/h over 10 seconds, so (20 km/h / 10 s) = 2 km/h/s. You increased your speed 2 km/h each second.
Directional force is:
Fd is directional, or down the plane, parallel to the plane, along the plane
Describe what NET force is
the resultant force after you consider the combination of all the forces acting on an object
If you throw a ball straight up, what is the acceleration at the very top?
10 m/s2 this acceleration is forever present at the earth’s surface
SATELLITES: How much does the earth curve over 8 km?
about 5 meters
Give an example of Newton’s third law in real life:
the floor is pushing up on you as much as you are pushing down on the floor
SATELLITES: How far up is the international space station?
400 km (250 miles)
block on inclined plane: What is Fd and FN?
Fd is force down plane along the slope, FN is normal force directly into the plane
What is the unit of weight we use?
NEWTON
Why do we say motion is relative?
You can only measure the motion of an object by relating it to another object. We are always in motion: spinning ‘round the earth, ‘round the sun, ‘round the galaxy, and away form all other matter in the universe!!!! So we generally measure motion relative to the earth.
what are the angle measures of the 1- sqrt 3- 2 triangle?
30- 60- 90 (across from those sides respectively)
If we know the horizontal and vertical component of a thrown baseball, how can we find the initial velocity?
Use the PYTHAGOREAN THEOREM v = sqrt (h squared + v squared)
What is the net force on an object moving at a constant velocity? Why?
zero (not accelerating) but has kinetic energy!
Instantaneous speed vs. average speed?
Instantaneous speed is what you see on a car’s speedometer. It is the speed an object is traveling at one moment in time. The average speed is the average speed of an entire trip, the average speed over an amount of time.
How can I remember relationship between time, distance and velocity?
My dog is in Vermont and my dog’s name is Vermont. d = vt
What is the net force on an object that is moving at its terminal velocity? Explain
zero. it is not accelerating
What is Newton’s Second Law?
a= F/m Force increases acceleration, mass resists accelertion
If you throw a ball up at 80m/s, how fast will it be going when you catch it?
80 m/s
How do we find the components if we have the resultant?
Generally, the resultant is the hypotenuse of a right triangle. So the closest side (adjacent) to the angle can be found by HYPcos(angle) and the opposite side (across) from the known angle can be found by HYPsin(angle)
What are the units in a NEWTON?
kg*m/s2
Vectors have both _____ and _____
magnitude and direction
What is the net force on an object at rest?
zero (not accelerating), but has potential energy!
If you throw a ball straight up, what is the velocity at the very top?
zero
What is a clever way to look at projectile motion?
Imagining the projectile as a free falling object from different places along a straight diagonal line drawn at initial angle
What are the side lengths of the 37-53-90 triangle?
3-4 and 5
If a bullet is shot horizontally at the exact time another is just dropped from the same height right next to it, which will land first (on flat surface)?
they will land at the same time
What is terminal velocity?
the highest speed a falling object will reach because of air resistance
What are the 3-4-5 right triangle angle measures
ABOUT: 37-53-90. (across from those sides respectively)
Special triangles?
3-4-5 (37-53-90), 1-1- sqrt 2 (45-45-90), 1-sqrt 3- 2 (30-60-90)
What is speed?
how much distance is covered over a period of time
When drawing velocity vectors along the path of a projectile, what doesn’t change?
The horizontal vectors stay the same
What does it mean by 10m/s2 ? Explain the “second squared” part
It is actually not really a squared second. Think of it as “10 m/s per second.” Velocity increases by 10 m/s for every second an object falls towards earth.
a newton divided by a mass (kg) will give you
an acceleration (m/s2)
What is acceleration? give a example.
Acceleration is a CHANGE OF VELOCITY. Example: In a car you increase your speed from 30 km/h to 50 km/h over a period of 4 seconds. Your speed changed 20 km/h over a period of 4 seconds. Your ACCELERATION was (20 km/h) / (4 s) = 5 km/ h/ s. Your speed increased 5 km/h each second.
SATELLITES: Why do we have to be above earth’s atmosphere to orbit?
Traveling 5 miles in a second, or 8km, air resistance makes it impossible. things would burn up (like shooting stars do)
what is a “horizontal range?”
the distance a projectile travels along the ground (horizontally)
What are the units we use for mass?
kg
A plane traveling north at 300 km/h with no wind: What is landspeed?
landspeed is 300km/h and airspeed is still 300km/h
What is Newton’s Third Law?
Every action (force) has an equal and opposite reaction
What is the unit of force we use?
NEWTON
Give an example of what accelerating at 5 km/h/s means
If an object is moving at 20 km/h and accelerates at 5km/h/s, it will be moving 25 km/h a second later and 30 km/h a second after that.
If you are given a force and an acceleration, you can find ____ by using the equation ____
mass, m= F/a
Normal force is:
FN is normal force, it is perpendicular to the plane (straight down into the plane). This determines amount of friction.\
what are the units we use for acceleration?
m/s2
Discuss the horizontal component of a thrown baseball.
Because we ignore air resistance, we assume that the baseball moves at constant velocity horizontally
The vector given is usually the ________ of the triangle.
hypotenuse
Plane traveling north at 300 km/h hits headwind of 100km/h. What is landspeed? airspeed?
landspeed is 200km/h and airspeed is still 300km/h
If you throw a ball up at 80m/s, how far up will it go?
40 m/s (8 seconds) = 320 meters
How fast are airplanes in m/s? (mph?) [km/h?]
250+ m/s (500+ mph) [800+km/h]
What is the acceleration due to gravity at the earth’s surface?
about 10 m/s2 (actually 9.8 m/s2)
What receives a greater force of air resistance, an elephant or a feather falling? Why?
elephant. it is pushing through more air
If you throw a ball up at 80m/s, what will be average speed on the way up?
(80 + 0 ) / 2 = 40 m/s
Give examples of vector quantities.
Velocity, acceleration, and force.
SOH CAH TOA… What do these stand for?
Sin angle= opp/hyp cos angle= adj/hyp tan angle= opp/ adj
The force of friction always acts____
in the opposide direction of motion
What is the net force on a 10kg object that is accelerating at 2 m/s2
F = ma so 10(2) = 20N
Give example of what accelerating at 10m/s2 means
If an object is falling at a specific time at a speed of 50 m/s, it will be falling 60 m/s a second later, and 70 m/s a second after that.
If you are given a mass and an acceleration, you can find ____ by using the equation ____
Force, F= ma
You can calculate the force of friction by multplying ____ by ____
normal force by coefficient of friction
SATELLITES: How fast does the international space station move?
28,000 km/h about 8 km/s . (17,500 mph, about 5 miles per second)
What angle of elevation maximizes horizontal range?
45 degrees.
If you drop a ball from rest, how fast is it moving after 1s ? 2s ? 5s?
final velocity = 10(time). So… 10 m/s, 20m/s and 50m/s
Describe magnitude and direction.
Magnitude answers “how much?” and direction answers “which way?”
What force do you need to accelerate a 1000kg car 5 m/s2 ? (ignore friction)
5000N
If you throw a ball up at 80m/s, how long will it be in the air before you catch it?
16 seconds
When is a projectile traveling the slowest?
At the top
A thrown baseball has has two velocity components. Describe them
A vertical component and a horizontal component. The vertical component and the horizontal components are independent, so they do not act on eachother.
If you have weight, how do you find normal force?
w*cos (angle) gives normal force.
How can you change velocity when driving? (three ways)
Hitting the gas (speeding up), hitting the brakes (slowing down) or TURNING. A change in direction is a change in velocity.
A plane traveling north at 300 km/h airspeed hits easterly wind of 400 km/h. What is landspeed?
Landspeed is the diagonal of triangle with sides 300 and 400, using 3-4-5 triangle, the diagonal is 500km//h. The airspeed is still 300km/h
What is the mass of an object that acceleraties 5 m/s2 when a 30N force is applied?
m= F/a so 30/ 5 = 6kg
What are the three equations from newton’s second law? (my fish is from massachusetts)
a=F/m F= ma F/a = m
Is acceleration scalar or vector?
vector (has direction and magnitude)
What will the acceleration be of an 800kg car that is pushed with a force of 8000N? (ignore friction)
10m/s2
Give an example of Newton’s first law in real life:
an apple on a desk. net force is zero, until you push it off
What did Galileo discover at the leaning tower of Pisa?
That all objects accelerate towards earth at the same rate, regardless of the mass of the object (when you ignore air resistance).
What are the three equations you can get from “My dog is in Vermont?”
- d=vt 2. d/v =t 3. d/t=v
When drawing velocity vectors along the path of a projectile, how does the vertical vector change?
Gravity impacts it. They become shorter on the way up, and ZERO at top, then get longer on the way down (pointing down) The velocity changes every second (10m/s each second). IT BECOMES ZERO AT THE TOP
Coefficients of friction are _____ for surfaces that are smooth and ____ for surfaces that are rough, or sticky.
smaller, larger
Give an example of Newton’s second law in real life:
harder to push a car than to push an apple
1 meter per second is about ______ mph and about ____ km/h
1 m/s = 2.2 mph = 3.6 km/h (about 1 m/s = 2 mph = 3 km/h)
