Concept Quiz 6

The kinetic energy of a body is correctly given by which of the following expressions? - mv. - 2mv^2 - mv^2 - (½)mv^2 - (½)mv.

(1⁄2)mv^2.

If work was done on an object, the object must have - changed only its direction of motion. - experienced a frictional force. - accelerated. - changed its position

Change its position

A mass hangs on a spring held in physicist's hand. When the mass is pulled down and then released, it oscillates with a period of 2.0 s. This system is taken to the Moon where the acceleration of gravity is less. The spring on the Moon is held in astronaut's hand, and the mass, when pulled down and released, will - oscillate with a longer period. - oscillate with an unchanged period. - oscillate with a shorter period. - will not oscillate at all.

oscillate with an unchanged period.

A mass attached to a spring is drawn back 2 cm and released. If a second spring were used that had a smaller spring constant than the first but the mass was the same, what would be larger? - Frequency - Initial restoring force - Period

period

Suppose you climb the stairs of a eight-story building, about 24 m high, and your mass is 70 kg. The gravitational potential energy you gain is about A. 16,500 calories. B. 16,500 Joule. C. 40 Joule. D. 40 calories.

16,500 Joule.

A 20 N ball and a 40 N ball are dropped at the same time from a height of 10 meters. Air resistance is negligible. Which of the following statements is accurate? - After 1 second has elapsed, both balls have the same kinetic energy since they have the same acceleration. - The heavy ball has a greater acceleration and falls faster. - The light ball has a greater speed since it can accelerate faster than the heavy ball. - Both balls hit the ground at the same time but gravity does more work on the heavy ball than on the light ball.

Both balls hit the ground at the same time but gravity does more work on the heavy ball than on the light ball.

Initially, a blue automobile has twice the kinetic energy that a red automobile has. Both are braked to a stop; both have the same amount of braking force. The red auto will stop in ____________________ as the blue auto. - half the distance - the same distance - twice the distance - four times the distance - one fourth the distance

Half the distance

A brick slides across a horizontal rough surface and eventually comes to a stop. What happened to the kinetic energy of the brick? - Nothing, it is still in the brick but is now called potential energy. - It was converted to other energy forms, mostly heat. - It was converted to a potential energy of friction. - It was simply destroyed in the process of stopping.

It was converted to other energy forms, mostly heat.

Which of the following is not a unit of power? - watt - kilowatt - kilowatt-hour - joule/second - horsepower

KiloWatt-hour

Which of the following is possessed by moving object, but not by a stationary object? - Energy. - Kinetic energy. - Mass. - Inertia.

Kinetic energy

Can the gravitational force of Earth do positive or negative work on a geosynchronous communication satellite, once it is on its circular orbit? - No, because the force is always perpendicular to the orbital path. - Yes, because its speed is constant. - No, because the satellite has zero acceleration. - Yes, because centripetal forces always do positive work.

No, because the force is always perpendicular to the orbital path

A mass hangs from a spring that is fixed to the ceiling. The mass is now pulled down and released so the mass oscillates up and down. Which of the following statements is true? - The kinetic energy of the oscillating mass is a constant. - Adding mass to the spring will make it oscillate faster. - The restoring force of the spring is equal to the weight of the mass. - The gravitational force on the mass oscillates at the same frequency as the mass. - None of these is true.

None of these is true.

A body is suspended from a spring hanging vertically. The body is then pulled downward so the spring stretches. Consider the change in the elastic potential energy (EPE) of the spring and the change in gravitational potential energy (GPE) as the body is pulled down. - The EPE increases but the GPE is unchanged. - The GPE increases along with the EPE. - The GPE decreases while the EPE increases. - The GPE decreases but the EPE is unchanged. - Both the GPE and the EPE decrease.

The GPE decreases while the EPE increases.

A block sits on a slight incline, held at rest by the frictional force between the block and the incline. Which of the following statements is true? - The frictional force performs no work since there is no motion of the block. - The work by the frictional force is equal to the gravitational potential energy of the block. - The work done by the frictional force is negative since the force of friction opposes the direction that the block is being tugged by gravity. - The work done by gravity is entirely converted into heat because of the friction present. - None of these are true.

The frictional force performs no work since there is no motion of the block.

On a frictionless tabletop, a force is applied to an object: the object's velocity is horizontal and the force is perpendicular to the tabletop. What is true about this? - There cannot be more than one force on the object. - The applied force is friction. - The force does work on the object. - The total energy of the object does not change.

The total energy of the object does not change.

Work is done on an object to increase its total energy. Which of the following is true? - the object must have a larger speed and smaller height above the ground. - both the kinetic energy and potential energy can be larger. - if the potential energy increases, then the kinetic energy must decrease. - the total work done must be equal to the energy lost to heat and sound.

The total work done must be equal to the energy lost to heat and sound.

When work is done by a force on an object, then which of the following are true? - The speed of the object always increases. - The mass of the object always increases. - The object does negative work on the force. - The energy lost to friction is equal to the amount of work done by the force. - The work done will be equal to the change of the total energy of the object plus energy appearing as heat, light, or sound.

The work done will be equal to the change of the total energy of the object plus energy appearing as heat, light, or sound.

Virgil rides a skateboard (combined mass 100 kg) at 4 m/s, and Jill rides a bicycle (combined mass 64 kg) at 5 m/s. - Virgil has the greater kinetic energy. - Virgil and Jill have equal kinetic energies. - Jill has the greater kinetic energy.

Virgil and Jill have equal kinetic energies.

Which of the following is not an energy unit? - N·m - Joule - calorie - watt - kWh

Watt

In order for a body to exhibit simple harmonic motion there must be - a constant force pushing the body away from the center. - a constant force drawing the body toward the center. - a force drawing the body toward the center and increasing with distance away from the center. - a force pushing the body away from the center and increasing with distance away from the center. - a force drawing the body toward the center and decreasing with distance away from the center

a force drawing the body toward the center and increasing with distance away from the center.

A worker in a warehouse uses a rope passing through some pulleys to lift a heavy crate. The worker exerts a force five times less than the weight of the crate but has to move the rope four times as far as the crate moves. This situation - cannot happen because the work done by the worker is less than the work done on the crate. - can happen because the extra distance traveled makes up for the smaller force applied. - can happen because there is friction in the pulleys so the work done by the worker will not equal the work done on the crate. - cannot happen because a crate that heavy would lift the worker, rather than the worker lifting the crate.

cannot happen because the work done by the worker is less than the work done on the crate.

A child riding on a swing rises to a height 1.0 m above the lowest point. Another child of equal mass whose speed at the lowest point is twice as great will rise - to the same height. - twice as high. - four times as high. - to a height which depends on the mass.

four times as high.

A box is pushed across a rough horizontal floor by a force acting parallel to the floor in the direction of motion. A force doing negative work on the body is - gravity. - friction. - the applied force. - normal reaction force of floor upward on body. - a fictitious force.

friction.

A box is pushed across a rough horizontal floor by a force acting parallel to the floor in the direction of motion. A force doing no work during the motion is - gravity. - friction. - the applied force. - all of the forces are doing work

gravity

If an object has a larger potential energy than kinetic energy, - the speed of the object will decrease. - the speed of the object will increase. - the speed of the object will not change. - it is not possible to predict what the speed will be; it depends on the situation.

it is not possible to predict what the speed will be; it depends on the situation.

A simple machine allows you to move _____ masses even though you apply ________. - larger; smaller force at less distance. - smaller; potential energy deficits. - stationary but not moving; many Newtons of force. - smaller; kinetic energy spread over the entire path.

larger; smaller force at less distance

A grandfather clock that is regulated by a pendulum is orbiting the Earth aboard the space station. Compared to an identical clock on Earth, the grandfather clock aboard the space station will - run slow. - keep time at the same rate. - run fast. - not run at all.

not run at all.

A mass hangs on a spring held in physicist's hand. When the mass is pulled down and then released, it oscillates with a period of 2.0 s. This system is taken to the space station orbiting the Earth. The spring is held in astronaut's hand, and the mass, when pulled down and released, will - oscillate with a longer period. - oscillate with unchanged period. - oscillate with a shorter period. - will not oscillate at all.

oscillate with unchanged period.

A grandfather clock that is regulated by a pendulum is taken to the Moon where the acceleration of gravity is less. Compared to an identical clock on Earth, the grandfather clock on the Moon will - run slow. - keep time at the same rate. - run fast.

run slow.

A ball at the end of a string is swinging as a simple pendulum. Assuming no loss in energy due to friction, we can say for the ball that - the kinetic energy does not change but the potential energy does. - the mechanical energy changes and is maximum where the kinetic energy is a minimum. - the mechanical energy changes and is maximum where the kinetic energy is maximum. - the potential energy is maximum at each end of the motion.

the potential energy is maximum at each end of the motion.

The power of an engine is a measure of - its volume. - its ability to outperform a horse. - the rate at which it can perform work. - the total amount of work it can perform.

the rate at which it can perform work.

Two springs are hung from a ceiling and carry identical masses. The first spring has a spring constant twice as large as the second spring. The masses on each spring are pulled down the same distance and are then released. The amplitude of the oscillation is - larger for the second spring. - the same for both springs. - larger for the first spring. - it is not possible to know which is larger without knowing the mass.

the same for both springs.

If the kinetic energy of an object increases, then - there can only be one force on the object. - the speed must increase as well. - the total energy must increase - the potential energy must decrease.

the speed must increase as well