Chapter 10 Prelecture

Gravitational potential energy is... A. mass times the acceleration due to gravity times vertical position. B. velocity per unit mass. C. the area under a gravity force-versus-time graph. D. the gravitation constant times mass-squared divided by distance-squared. C. 1/2 mass times speed-squared.

Mechanical energy is 1 the energy due to internal moving parts. 2 the energy of motion. 3 the sum of kinetic energy plus potential energy. 4 the energy of position. 5 the sum of kinetic, potential, thermal, and elastic energy.

For conservative forces, Force can be found as being the negative of the derivative of 1 kinetic energy. 2 momentum. 3 work. 4 impulse. 5 potential energy.

Rank in order, from largest to smallest, the gravitational potential energies of the balls. A 1 > 2 = 4 > 3 B 3 > 2 = 4 > 1 C 3 > 2 > 4 > 1 D 1 > 2 > 3 > 4

As the projectile goes upward, what energy changes take place? 1 Both kinetic and potential energy decrease. 2 Both kinetic and potential energy increase. 3 Kinetic energy decreases; potential energy increases. 4 Kinetic energy increases; potential energy decreases.

At the top point of the flight, what can be said about the projectile's kinetic and potential energy? 1 Both kinetic and potential energy are at their maximum values. 2 Both kinetic and potential energy are at their minimum values. 3 Kinetic energy is at a maximum; potential energy is at a minimum. 4 Kinetic energy is at a minimum; potential energy is at a maximum.

The potential energy of the object at the moment of launch __________. 1 is negative 2 is positive 3 is zero 4 depends on the choice of the "zero level" of potential energy

Suppose our experimenter repeats his experiment on a planet more massive than Earth, where the acceleration due to gravity is g=30 m/s2. When he releases the ball from chin height without giving it a push, how will the ball's behavior differ from its behavior on Earth? 1 It will take more time to return to the point from which it was released. 2 Its mass will be greater. 3 It will take less time to return to the point from which it was released. 4 It will smash his face. 5 It will stop well short of his face.

The force acting on the particle at point A is __________. 1 directed to the right 2 directed to the left 3 equal to zero

The force acting on the particle at point C is __________. 1 directed to the right 2 directed to the left 3 equal to zero

The force acting on the particle at point B is __________. 1 directed to the right 2 directed to the left 3 equal to zero

The acceleration of the particle at point B is __________. 1 directed to the right 2 directed to the left 3 equal to zero

If the particle is located slightly to the left of point B, its acceleration is __________. 1 directed to the right 2 directed to the left 3 equal to zero

If the particle is located slightly to the right of point B, its acceleration is __________. 1 directed to the right 2 directed to the left 3 equal to zero

Name all labeled points on the graph corresponding to unstable equilibrium.

Name all labeled points on the graph corresponding to stable equilibrium.

Name all labeled points on the graph where the acceleration of the particle is zero.

Name all labeled points such that when a particle is released from rest there, it would accelerate to the left.

Consider points A, E, and G. Of these three points, which one corresponds to the greatest magnitude of acceleration of the particle?

What point on the graph corresponds to the maximum kinetic energy of the moving particle?

At what point on the graph does the particle have the lowest speed?

At which of the three points labeled in the figure is the magnitude of the force on the particle greatest?

Which, if any, of the following statements concerning the work done by a conservative force is NOT true? 1 It can always be expressed as the difference between the initial and final values of a potential energy function. 2 When the starting and ending points are the same, the total work is zero. 3 It is independent of the path of the body and depends only on the starting and ending points. 4 All of the above statements are true.

If the force on a particle at some point in space is zero, must its potential energy also be zero at that point? Y/N

If the potential energy of a particle at some point in space is zero, must the force on it also be zero at that point? Y/N

A roller-coaster car rolls down a frictionless track, reaching speed v_0 at the bottom. If you want the car to go twice as fast at the bottom, by what factor must you increase the height of the track? A You must increase the track height by a factor of 2. B You must increase the track height by a factor of 3. C You must increase the track height by a factor of 4.

Can kinetic energy ever be negative? Y/N

Can gravitational potential energy ever be negative? Y/N

Is it possible for a system to have negative potential energy? 1 Yes, as long as the total energy is positive. 2 No, because this would have no physical meaning. 3 Yes, since the choice of the zero of potential energy is arbitrary. 4 Yes, as long as the kinetic energy is positive. 5 No, because the kinetic energy of a system must equal its potential energy.

Upon what basic quantity does kinetic energy depend? 1 Position 2 Motion 3 Size 4 Force

Upon what basic quantity does potential energy depend? 1 Force 2 Size 3 Motion 4 Position

The same ball is shot straight up a second time from the same gun, but this time the spring is compressed only half as far before firing. How far up does the ball go this time?

The work-energy theorem states that a force acting on a particle as it moves over a ______ changes the ______ energy of the particle if the force has a component parallel to the motion. 1 distance / potential 2 distance / kinetic 3 vertical displacement / potential 4 none of the above

To calculate the change in kinetic energy, you must know the force as a function of _______. The work done by the force causes the kinetic energy change. 1 acceleration 2 work 3 position 4 potential energy

To illustrate the work-energy concept, consider the case of a stone falling from x_i to x_f under the influence of gravity. Using the work-energy concept, we say that work is done by the gravitational _____, resulting in an increase of the ______ energy of the stone. 1 force / kinetic 2 potential energy / potential 3 force / potential 4 potential energy / kinetic

Rather than ascribing the increased kinetic energy of the stone to the work of gravity, we now (when using potential energy rather than work-energy) say that the increased kinetic energy comes from the ______ of the _______ energy. 1 work / potential 2 force / kinetic 3 change / potential

This process happens in such a way that total mechanical energy, equal to the ______ of the kinetic and potential energies, is _______. 1 sum / conserved 2 sum / zero 3 sum / not conserved 4 difference / conserved