# Physics HW Conceptual Questions

The flashcards below were created by user karoublue on FreezingBlue Flashcards.

1. A juggler throws a bowling pin straight up in the air. After the pin
leaves his hand and while it is in the air, which statement is true?
The velocity of the pin is opposite its acceleration on the way up.
2. A racing car starts from rest and reaches a final speed v in a time t. If the acceleration of the car is constant during this time, which of the following statements must be true?
• The acceleration of the car is v/t.
• The average speed of the car is v/2.
3. When the pilot reverses the propeller in a boat moving north, the boat
moves with an acceleration directed south. Assume the acceleration of
the boat remains constant in magnitude & direction. What happens to
the boat?
It eventually stops and then speeds up in the southward direction.
4. Which of the following quantities are vectors?
the velocity of a sport car

the displacement of a tennis player from the backline of the court to the net
5. A baseball is thrown from the outfield toward the catcher. When the ball reaches its highest point, which statement is true?
Its velocity is perpendicular to its acceleration.
6. A NASA astronaut hits a golf ball on the Moon. Which of the following
quantities, if any, remain constant as the ball travels through the
lunar vacuum?
• horizontal component of velocity
• acceleration
7. As a block slides down a frictionless incline, which of the following statements is true?
Its speed increases and its acceleration remains constant.
8. If Earth's mass and radius both suddenly doubled, what would be the new
value of the acceleration of gravity near Earth's surface?
4.90 m/s2
9. If a constant non-zero net external force acts on an object during a
given period, which of the following statements must be true during that
time?
• The object accelerates.
• The object moves.
10. If an object of mass m moves with constant velocity v, the net force on the object is which the following?
Fnet= 0
11. A large crate of mass m is placed on the back of a truck but not tied down. As the truck accelerates forward with an acceleration a, the crate remains at rest relative to the truck. What force causes the crate to accelerate forward?
the force of friction between the crate and the floor of the truck
12. If the slide were not frictionless, would the shape of the slide affect the final answer?
yes.
13. In general, are the minimum
power requirements of an elevator car ascending at constant velocity
greater than, less than, or equal to the minimum power requirements of
an elevator car descending at constant velocity?
greater than
14. If the speed of a particle is doubled, what happens to its kinetic energy?
It becomes four times larger.
15. A certain truck has twice the mass of a car. Both are moving at the same speed. If the kinetic energy of the truck is K, what is the kinetic energy of the car?
K/2
16. If the net work done on a particle is zero, which of the following statements must be true?
The speed is unchanged.
17. A block of mass m is dropped from the fourth floor of an office building, subsequently hitting the sidewalk at speed v. From what floor should the mass be dropped to double that impact speed?
the sixteenth floor
18. When a person is involved in a
car accident, why is the likelihood of injury greater in a head-on
collision as opposed to being hit from behind?
• The change in momentum is greater in the head-on collision.
• The average force on the driver is greater in the head-on collision.
19. Is it possible to adjust the initial velocities of the balls so that both final velocities are zero?
• No, because energy is conserved and requires the total kinetic energy to be non-zero.
• No, because energy is conserved and that requires one ball or both to be moving after the collision.
20. In a game of billiards, a red billiard ball is traveling in the positive x-direction with speed v and the cue ball is traveling in the negative x-direction with speed 3v when the two balls collide head on. Which statement is true concerning their velocities subsequent to the collision?
red ball: −3v; cue ball: v
21. If two particles have equal kinetic energies, are their momenta equal?
Yes, if both their masses and directions of motion are the same.
22. If two particles have equal momenta, are their kinetic energies equal?
No, except when their masses are equal
23. If the angular acceleration were doubled for the same duration, by what factor would the angular displacement change?
2
24. If the force causing the centripetal acceleration suddenly vanished, the car would
proceed along a line tangent to the circular motion
25. Select two reasons Equation (1) could not be used for every asteroid as it was in part (B)
• The asteroid may be too small to have a significant or useful region with constant gravitational acceleration.
• The asteroid may be too non-spherical to have a constant gravitational acceleration.
26. An object is located on the surface of a spherical planet of mass M and radius R. The escape speed from the planet does not depend on which of the following?
the mass of the object
27. A satellite moves in a circular orbit at a constant speed around Earth. Which of the following statements is true?
The satellite has an acceleration directed toward Earth.
28. Which of the following statements are true of an object in orbit around Earth?
• If the orbit is circular, the gravity force is perpendicular to the object's velocity.
• If the orbit is elliptical, the gravity force is perpendicular to the velocity vector only at the nearest and farthest points
 Author: karoublue ID: 271403 Card Set: Physics HW Conceptual Questions Updated: 2014-04-22 00:53:47 Tags: physics conceptualizations Folders: science Description: conceptual understanding Show Answers: