Exam 2 review- misconceptual Qs
Bill & his daughter Susan are both standing on identical skateboards, initially at rest. Bill weighs 3 times as much as Susan. Bill pushes horizontally on Susan's back, causing Susan to start moving away from Bill. Just after Bill stops pushing, _________
Susan and Bill are moving away from each other & Susan's speed is 3 times that of Bill
What points towards the center of the circle in uniform circular motion?
acceleration, net force
Which pulls harder gravitationally, the Earth on the Moon, or the Moon on the Earth? Which accelerates more?
both the same; the Moon
A truck going 15 km/h has a head-on collision with a small car going 30 km/h. Which best describes the situation?
they both have the same change in magnitude of momentum because momentum is conserved
A car accelerates from rest to 30 km/h. Later, from 30 to 60 km/h. Which takes more energy?
30 to 60 km/h
When the speed of your car is doubled, by what factor does its kinetic energy increase?
4
A car traveling at a velocity v can stop in a minimum distance d. What would be the car's minimum stopping distance if it were traveling at a velocity of 2v?
4d
You & your friend, who weighs the same as you, want to go to the top of the Eiffel Tower. Your friend takes the elevator straight up. You decide to walk up the spiral stairway, taking longer to do so. Compare the gravitational potential energy of you & your friend, after you both reach the top.
Both of you have the same amount of gravitational potential energy at the top
2 small balls, A & B, attract each other gravitationally with a force of magnitude F. If we now double both masses & the separation of the balls, what will now be the magnitude of the attractive force on each one?
F
A satellite in circular orbit around the Earth moves at constant speed. This orbit is maintained by the force of gravity between the Earth and the satellite, yet no work is done on the satellite. How is this possible?
No work is done if the direction of motion is perpendicular to the force
A child whirls a ball in a vertical circle. Assuming the speed of the ball is constant, when would the tension in the cord connected to the ball be greatest?
at the bottom of the circle
2 balls are thrown off a building with the same speed, 1 straight up & 1 at a 45 degree angle. Which statement is true if air resistance can be ignored?
both hit the ground with the same speed
A small boat coasts at constant speed under a bridge. A heavy sack of sand is dropped from the bridge onto the boat. The speed of the boat:
decreases
Joe & Bill throw identical balls vertically upward. Joe throws his ball with an initial speed twice as high as Bill. If there is no air resistance, the maximum height of Joe's ball will be ________
equal to that of Bill's ball
A ball is thrown straight up. At what point does the ball have the most energy? Ignore air resistance.
everywhere- the energy of the ball is the same at all of these points
While driving fast around a sharp right turn, you find yourself pressing against the car door. The door is ________
exerting a rightward force on you
A golf ball and an equal-mass bean bag are dropped from the same height and hit the ground. The bean bag stays on the ground while the golf ball rebounds. Which experiences the greater impulse from the ground?
golf ball
A railroad car collides with and sticks to an identical railroad car that is initially at rest. After the collision, the kinetic energy of the system ________
is half as much as before
The moon does not crash into the Earth because
it is freely falling but it has a high tangential velocity
A space shuttle in orbit around the Earth carries its payload with its mechanical arm. Suddenly, the arm malfunctions & releases the payload. What will happen to the payload?
it will follow a curved path & eventually hit the Earth
A man pushes a block up an incline at a constant speed. As the block moves up the incline, _________
its potential energy increases & its kinetic energy remains the same
A railroad tank car contains milk & rolls at a constant speed along a level track. The milk begins to leak out the bottom. The car then:
maintains a constant speed
2 identical billiard balls traveling at the same speed have a head-on collision & rebound. If the balls had twice the mass, but maintained the same size & speed, how would the rebound be different?
no difference
A bowling ball is dropped from a height h onto the center of a trampoline, which launches the ball back up into the air. How high will the ball rise?
no more than h- probably a little less
You push very hard on a heavy desk, trying to move it. You do work on the desk:
only if it starts moving
A space vehicle, in circular orbit around the Earth, collides with a small asteroid which ends up in the vehicle's storage bay. For this collision:
only momentum is conserved
A car drives at steady speed around a perfectly circular track. Both the acceleration & net force on the car __________
point inward
Two satellites orbit the Earth in circular orbits of the same radius. One satellite is twice as massive as the other. Which statement is true about the speeds of these satellites?
the 2 satellites have the same speed
In the International Space Station which orbits Earth, astronauts experience apparent weightlessness because
the astronauts & the station are in free fall towards the center of the Earth
A baseball is pitched horizontally toward home plate with a velocity of 110 km/h. In which scenario does the change in momentum of the baseball have the largest magnitude?
the baseball is hit straight back to the pitcher at a speed of 110 km/h
You are laying in bed and want to shut your bedroom door. You have a bouncy ball & a blob of clay, both with the same mass. Which one would be more effective to throw at your door to close it?
the bouncy ball
You push a heavy crate down a ramp at a constant velocity. Only four forces act on the crate. Which force does the greatest magnitude of work on the crate?
the force of gravity
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
An object of mass m rests on a flat table. The earth pulls on this object with a force of magnitude mg. What is the reaction force to this pull?
the object pulling upward on the Earth with force mg
A ball is thrown straight up. Neglecting air resistance, which statement is NOT true regarding the energy of the ball?
the potential energy decreases while the ball is going up
Engines are rated in horsepower. What is this?
the rate at which the engine can do work
A small car meshes with a large truck in a head-on collision. Which of the following statements concerning the magnitude of the momentum change during the collision is correct?
the small car & the truck experience the same magnitude momentum change
A small car and a heavy pickup truck are both out of gas. The truck has twice the mass of the car. If you push both the car & truck for the same distance with the same force, what can you say about the momentum and kinetic energy of the car and the truck?
they have the same kinetic energy, but the truck has more momentum than the car
A small car and a heavy pickup truck are both out of gas. The truck has twice the mass of the car. After you push both the car and the truck for the same amount of time with the same force, what can you say about the momentum and kinetic energy of the car and the truck? Ignore friction.
they have the same momentum, but the car has more kinetic energy than the truck
An astronaut is a short distance away from her space station without a tether rope. She has a large wrench. What should she do with the wrench to move toward the space station?
throw it directly away from the space station