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Mike attaches a 3.00 kg lead ball to a string to make a pendulum of length 10.0 meters. Let us call the position at which

Mike attaches a 3.00 kg lead ball to a string to make a pendulum of length 10.0 meters. Let us call the position at which the lead ball hangs down vertically and is at rest the equilibrium position. Mike then pulls the lead ball to the side so that its center is raised to a vertical height of 0.0409 meters above its equilibrium position, and he gives the lead ball (pendulum bob) a push. Thus Mike gives the pendulum bob an initial kinetic energy of 2.00 J as he releases it. Assume there is no air resistance or friction. Choose the reference level for potential energy at the bottom of the pendulum's swing (the equilibrium position). What is the total initial energy of the pendulum as Mike releases it?

a.

1.20 J

b.

2.00 J

c.

3.20 J

d.

4.40 J

e.

none of the items

Mike attaches a 3.00 kg lead ball to a string to make a pendulum of length 10.0 meters. Let us call the position at which the lead ball hangs down vertically and is at rest the equilibrium position. Mike then pulls the lead ball to the side so that its center is raised to a vertical height of 0.0409 meters above its equilibrium position, and he gives the lead ball (pendulum bob) a push. Thus Mike gives the pendulum bob an initial kinetic energy of 2.00 J as he releases it. Assume there is no air resistance or friction. Choose the reference level for potential energy at the bottom of the pendulum's swing (the equilibrium position). The maximum height the pendulum bob attains during each cycle is:

a.

about 0.068 meters higher than the position at which Mike released it.

b.

about 0.041 meters higher than the position at which Mike released it.

c.

about 0.021 meters higher than the position at which Mike released it.

d.

the same height as that at which Mike released it.

e.

lower than the height at which Mike released it.

A 10,000 kg railroad car and a 20,000 kg railroad car are rolling toward each other on a level, very low friction section of railroad track. The cars collide, lock together, and immediately stop motionless. In this collision:

a.

momentum was conserved, but kinetic energy was not conserved.

b.

kinetic energy was conserved, but momentum was not conserved.

c.

neither momentum nor kinetic energy were conserved.

d.

both momentum and kinetic energy were conserved.

e.

not enough information has been given to determine if either momentum or kinetic energy was conserved.

A 30-kg girl and a 40-kg boy are together, standing at rest on their ice skates on an ice skating rink. The boy pushes the girl, who moves away with a speed of 1.0 m/s relative to the ice. After he pushes the girl, the boy's speed relative to the ice is:

a.

0.55 m/s

b.

0.75 m/s

c.

1.20 m/s

d.

1.33 m/s

e.

none of the items

A 0.100 kg mass is hanging down from a spring. Sally then pulls the mass vertically downward another 5 centimeters and releases it, which causes the mass to oscillate up-and-down. Assume there is no friction. Which of the following statements is true about the mass-spring system?

a.

Its kinetic energy is greatest when the mass is at its highest point.

b.

Its kinetic energy is greatest when the mass is halfway between the highest and lowest points.

c.

Its kinetic energy is greatest when the mass is at its lowest point.

d.

Its potential energy is greatest when the mass is halfway between the highest and lowest points.

e.

Its total energy is greatest when the mass is at its highest point and smaller when the mass is halfway between the highest and lowest points.

A block slides down an inclined plane tilted an angle of 30 with respect to the horizontal. If there is no friction between the inclined plane and block, then the block's acceleration:

a.

increases as the block slides down the inclined plane.

b.

is constant.

c.

decreases to zero as the block slides down the inclined plane.

d.

decreases until a nonzero terminal velocity is attained.

e.

none of these items

A woman, whose normal weight on Earth's surface is 110.0 lbs. (= 489.5 N), is standing on a bathroom scale in an elevator.

Since the reading on the bathroom scale is 130 lbs., the elevator:

a.

must be going down at a constant speed.

b.

must be accelerating downward.

c.

must be going up at a constant speed.

d.

must be accelerating upward.

e.

none of these items

A 10 kg mass is hanging from a string, which is tied to the ceiling of a Boston University building. What is the force of tension on the string?

a.

10 N

b.

9.8 N

c.

98 N

d.

980 N

e.

none of these items

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