Chapter 7 & 8

The power required to exert 1 N force, over a distance of 1 m in 1 second is A) 1 W B) 2 W C) 1/3 W D) 3 W E) none of these

A) 1 W

On a balanced seesaw, a boy three times as heavy as his partner sits A) 1/3 the distance from the fulcrum B) less than 1/3 the distance from the fulcrum C) more than 1/3 the distance from the fulcrum

A) 1/3 the distance from the fulcrum

A machine puts out 100 watts of power for every 1000 watts put into it. The efficiency of the machine is A) 10% B) 50% C) 90% D) 110% E) none of these

A) 10%

Neglecting air resistance, a man on a high ladder releases a ball which strikes the ground with 100 J of kinetic energy. If he were to throw it straight upward instead, it will eventually reach the ground with a kinetic energy of A) 100 J B) more than 100 J C) less than 100 J

A) 100 J

The famous Leaning Tower of Pisa doesn't topple over because its center of gravity is A) above a place of support B) relatively low for such a tall building C) stabilized by its structure D) displaced from its center E) In the same place as its center of mass

A) above a place of support

A ball rolls down a hill mainly because of A) an unbalanced torque B) a balanced torque C) its rotational inertia D) its angular acceleration E) its angular momentum

A) an unbalanced torque

The center of gravity of a circular disk of sheet metal is A) at the center of the disk B) midway between the center and the outside C) two-thirds of the way between the center and the outside D) impossible to predict without knowing the metal density

A) at the center of the disk

If the Earth had two identical moons in one circular orbit, and the moons were as far apart in that orbit as they could be, the center of gravity of the Earth-moons system would be A) at the center of the earth B) inside the earth, but off center C) outside the earth, but within the orbital path of the moons D) outside the earth, but beyond the orbital path of the moons

A) at the center of the earth

If you balance a broom horizontally on one finger, the center of gravity of the broom will be above your finger, closer to the bristles end than the handle end. If you saw the broom in two pieces at that point and weigh the two parts on a scale, you'll find that the heavier part is the A) bristles part B) handle part C) both the same weight

A) bristles part

Your pet hamster sits on a record player whose angular speed is constant. If he moves to a point twice as far from the center, then his linear speed A) doubles B) halves C) remains the same

A) doubles

A flywheel's diameter is twice that of another of the same shape and mass. The larger flywheel's rotational inertia is A) four times the other's B) two times the other's C) the same as the other's D) half the other's

A) four times the other's

A clerk can lift containers a vertical distance of 1 meter or can roll them up a 2 meter-long ramp to the same elevation. With the ramp, the applied force required is about A) half as much B) twice as much C) the same D) four times s much

A) half as much

Consider a rotating donut-shaped space habitat where living quarters are on the inside surface farthest from the axis. If the rotational speed of the habitat increases, the apparent weight of people inside A) increases B) decreases C) stays the same D) is always zero

A) increases

When a twirling ice skater brings her arms inward, her rotational speed A) increases B) decreases C) remains the same

A) increases

A ball is projected into the air with 100 J of kinetic energy which is transformed to gravitational potential energy at the top of its trajectory. When it returns to its original level after encountering air resistance, its kinetic energy is A) less than 100 J B) more than 100 J C) 100 J D) not enough information given

A) less than 100 J

Stand a meter stick on its end and let go and it rotates to the floor. If you attach a heavy weight to its upper end and repeat, falling time will be A) more B) less C) the same

A) more

An object that has kinetic energy must be A) moving B) falling C) at an elevated position D) at rest E) none of these

A) moving

An industrial flywheel has a greater rotational inertia when most of its mass is A) nearest the rim B) nearest the axis C) uniformly spread out as in a disk

A) nearest the rim

If you push for a half hour or a whole hour against a stationary wall A) no work on the wall is done in either case B) half as much work is done during the half hour C) twice as much work is done during the half hour D) it is impossible to determine how much work is done

A) no work on the wall is done in either case

Two people are balanced on a seesaw. If one person leans inward toward the center of the seesaw, that person's end of the seesaw tends to A) rise B) fall C) stay at the same level D) rise and then fall E) fall and then rise

A) rise

The ball is rolling down an incline has its maximum potential energy at A) the top B) a quarter of the way down C) halfway down D) the bottom

A) the top

If you push an object a given distance, while applying twice the force, you do A) twice as much work B) four times as much work C) the same amount of work D) half as much work

A) twice as much work

If you push an object twice as far while applying the same force, you do A) twice as much work B) four times as much work C) the same amount of work D) half as much work

A) twice as much work

Put a pipe over the end of a wrench when trying to turn a stubborn nut on a bolt, to effectively make the wrench handle twice as long, you'll multiply the torque by A) two B) four C) eight

A) two

It takes 40 J to push a large box 4 m across a floor. Assuming the push is in the same direction as the move, what is the magnitude of the force on the box? A) 4 N B) 10 N C) 40 N D) 160 N E) none of these

B) 10 N

Do 100 J of work in 50 s and your power output is A) 1/2 W B) 2 W. C) 4 W. D) 50 W. E) 5,000 W.

B) 2 W.

A 2 kg mass has 40 J of potential energy with respect to the ground. Approximately how high is it above ground? A) 1 m B) 2 m C) 3 m D) 4 m E) none of these

B) 2 m

Suppose the circumference of a bicycle wheel is 2 meters. If it rotates at 1 revolution per second when you are riding the bicycle, then your speed will be A) 1 m/s B) 2 m/s C) 3 m/s D) 3.4 m/s E) 6.28 m/s

B) 2 m/s

Using 1000 J of work, a toy elevator is raised from the ground floor to the second floor in 20 seconds. The power needed to do this job was A) 20 W B) 50 W C) 100 W D) 1000 W E) 20,000 W

B) 50 W

A baseball bat is balanced on a fulcrum. The center of gravity of the bat is located A) closer to the handgrip B) above the fulcrum C) near the heavy end

B) above the fulcrum

A coin and a ring roll down an incline starting at the same time. The one to reach the bottom first will be the A) ring B) coin C) Bot reach the bottom at the same time

B) coin

A car travels in a circle with constant speed. The net force on the car is A) directed forward, in the direction of travel B) directed toward the center of the curve C) zero because the car is not accelerating D) none of these

B) directed toward the center of the curve

A tightrope walker more easily balances on a tightwire of his pole A) is held high B) droops C) is short but heavy

B) droops

A car that travels twice as fast as another when braking to a stop will skid A) twice as far B) four times as far C) depends on the mass of the cars

B) four times as far

The gravitational field best suited for humans living in an outer space colony is A) zero B) g C) one-quarter g D) one-half g E) three-quarters g

B) g

A broom is easier to balance on its end when the heavier end ( the brush end) is A) nearest your hand B) highest, farthest from your hand C) same either way

B) highest, farthest from your hand

Suppose you put very large-diameter tires on your car. The, your speedometer will show a speed that is A) higher than it is actually B) lower than it is actually C) the same as before

B) lower than it is actually

Horses that move with the fastest linear speed on a merry-go-round are located A) near the center B) near the outside C) anywhere, because they all move at the same speed

B) near the outside

A job is done slowly, while an identical job is done quickly. Both jobs require the same amount of work, but different amounts of A) energy B) power C) effort D) none of these

B) power

A torque acting on an object tends to produce A) equilibrium B) rotation C) linear motion D) velocity E) a center of gravity

B) rotation

Which has greater kinetic energy, a car traveling at 30 km/hr or a car of half the mass traveling at 60 km/hr A) the 30 km/hr car B) the 60 km/hr car C) Both have the same kinetic energy D) more information is needed about the distance traveled

B) the 60 km/hr car

Two identical arrows, one with twice the kinetic energy of the other, are fired into a bale of hay. The faster arrow will penetrate A) the same distance as the slower arrow B) twice as far as the slower arrow C) four times as far as the slower arrow D) more than four times as far as the slower arrow E) none of these

B) twice as far as the slower arrow

Consider a string with several rocks tied along its length at equally spaced intervals. You whirl the string overhead so that the rocks follow circular paths. Compared with a rock at the end of the string, a rock at the outer end moves A) half as fast B) twice as fast C) at the same linear speed

B) twice as fast

If an object is raised twice as high, its potential energy will be A) half as much B) twice as much C) the same D) impossible to determine

B) twice as much

A flywheel's mass is twice that of another of the same size and shape. The more massive flywheel's rotational inertia is A) four times the other's B) two times the other's C) the same as the other's D) half the other's

B) two times the other's

A bow is drawn so that it has 40 J of potential energy. When fired, the arrow will ideally have a kinetic energy that is A) less than 40 J B) more than 40 J C) 40 J D) impossible to predict without additional information

C) 40 J

A jack system will increase the potential energy of a heavy load by 1000 J with a work input of 2000 J. The efficiency of the jack system is A) 10% B) 20% C) 50% D) 80% E) Not enough information is given

C) 50%

Suppose you're on a Ferris wheel at a carnival, seated 10 m from the Ferris wheel's axis. If you make a complete rotation each minute, your linear speed is A) 10 m/min B) 31.4 m/min C) 62.8 m/min D) 100 m/min E) Not enough information is given

C) 62.8 m/min

What task requires the most work; lifting a 50-kg sack 2 meters or lifting a 25-kg sack 4 meters? A) the 50-kg sac B) the 25-kg sac C) Both require the same amount of work D) impossible to determine without knowing the contents of the sac

C) Both require the same amount of work

When doing somersaults, you'll more easily rotate when your body is A) straight with both arms above your head B) straight with both arms at your sides C) balled up D) no difference

C) balled up

Two identical arrows, one with twice the speed of the other, are fired into a hay bale. The faster arrow will penetrate A) the same distance as the slower arrow B) two times further than the slower arrow C) four times further than the slower arrow D) more than four times further than the slower arrow E) none of these

C) four times further than the slower arrow

a ball is rolling down an incline has its minimum speed A) at the end the incline B) half way down the incline C) near the top of the incline D) impossible to predict without knowing the ball's mass E) impossible to predict without knowing the size of the ball

C) near the top of the incline

What is the simulated gravitational field strength half-way between the axis of the Earth and the outside edge where the field strength is g? A) zero B) g C) one-half g D) three-quarters g

C) one-half g

A ring, a disk, and a solid sphere begin rolling down a hill together. The one to reach the bottom first is the A) ring B) disk C) sphere D) They all reach the bottom at the same time E) Not enough information is given

C) sphere

For a system in mechanical equilibrium A) the resultant force must be zero B) the resultant torques must be zero C) the resultant forces and torques must both be zero D) the resultant forces and torques must be equal

C) the resultant forces and torques must both be zero

Both a 50-kg sack is lifted 2 meters from the ground and a 25-kg sack is lifted 4 meters in the same time. The power expended in raising the 50-kg sack is A) twice as much B) half as much C) the same D) impossible to predict without further information

C) the same

A carnival has a Ferris wheel where the seats are located halfway between the center and outside rim. If you were at the outside rim, your angular speed while riding on this Ferris wheel would be A) less and your tangential speed more B) more and your tangential speed less C) the same and yous tangential speed less

C) the same and yous tangential speed less

After rolling halfway down an incline, a marble's kinetic energy is A) less than its potential energy B) greater than its potential energy C) the same as its potential energy D) impossible to determine

C) the same as its potential energy

An object lifted 10 meters gains 200 J of potential energy. If the same object is lifted 20 meters, its potential energy gain is A) half as much B) the same C) twice as much D) four times as much E) more than four times as much

C) twice as much

A 1000-kg car and a 2000-kg car are hoisted the same distance. Raising the more massive car requires A) less work B) as much work C) twice as much work D) four times as much work E) more than four times as much work

C) twice as much work

A 1-kg rock is suspended from the tip of a meter stick at the 0-cm mark so that the meter stick balances like a seesaw when the fulcrum is at the 25-cm mark. From this information, what is the mass of the meter stick. A) 1/4 kg B) 1/2 kg C) 3/4 kg D) 1 kg E) more than 1 kg

D) 1 kg

A car moves 4 times as fast as another identical car. Compared to the slower car, the faster car has A) 4 times the KE B) 8 times the KE C) 12 times the KE D) 16 times the KE

D) 16 times the KE

A TV set is pushed a distance of 2 m with a force of 20 N. How much work is done on the set? A) 2 J B) 10 J C) 20 J D) 40 J E) 800 J

D) 40 J

A diver who weighs 500 N steps off a diving board that is 10 m above the water. The diver hits the water with kinetic energy of A) 10 J B) 500 J C) 510 J D) 5000 J E) more than 5000 J

D) 5000 J

A 2-kg mass is held 4 m above the ground. What is the approximate potential energy of the mass with respect to the ground? A) 6 J B) 8 J C) 32 J D) 80 J E) none of these

D) 80 J

The long, heavy tail of a spider monkey enables the money to easily vary its A) weight B) momentum C) inertia D) center of gravity E) none of these

D) center of gravity

An object may have potential energy because of its A) speed B) acceleration C) momentum D) location E) none of these

D) location

Centrifugal forces are an apparent reality to observers in a reference frame that is A) moving at a constant velocity B) an inertial reference frame C) at rest D) rotating E) none of these

D) rotating

A ball is rolling down an incline has its maximum kinetic energy at A) the top B) halfway down C) three-quarters of the way down D) the bottom

D) the bottom

If you find that twice as much work is needed to perform a task but it takes twice as much time, the amount of power required is A) twice as much B) four times as much C) sixteen times as much D) unchanged

D) unchanged

A car moving at 50 km/hr skids 20 m with locked brakes. How far will the car skid with locked brakes if it were traveling at 150 km/hr A) 20 m B) 60 m C) 90 m D) 120 m E) 180 m

E) 180 m

Consider a hydraulic press. When the input piston is depressed 20cm, the output piston is observed to move 1 cm. On the same press, an input force of 1N can raise no more than A) 1 N B) 10 N C) 15 N D) 20 N E) All of the above are correct

E) All of the above are correct