Deck 5: Energy

Question 1

0.8A satellite is held in orbit by a 1,000-N gravitational force.Each time the satellite completes an orbit of circumference 80,000 km,the work done on it by gravity is:

A) 0.8×10⁸ J.
B) 0.8×10¹¹ J.
C) 0.13×10⁸ J.
D) 0.
E) ​0.13×10¹¹ J.

Answer 1

0.

Question 2

A student has to work the following problem: A block is being pulled along at constant speed on a horizontal surface a distance d by a rope supplying a force F at an angle of elevation q.The surface has a frictional force acting during this motion.How much work was done by friction during this motion? The student calculates the value to be -Fdsinq.How does this value compare to the correct value?

A) It is the correct value.
B) It is too high.
C) It is too low.
D) The answer cannot be found until it is known whether q is greater than,less than,or equal to 45°.

Answer 2

The answer cannot be found until it is known whether q is greater than,less than,or equal to 45°.

Question 3

A worker pushes a sled with a force of 37 N over a level distance of 5.0 m.If a frictional force of 21 N acts on the wheelbarrow in a direction opposite to that of the worker,what net work is done on the wheelbarrow?

A) 290 J
B) 185 J
C) 105 J
D) 80 J
E) ​3.2 J

Answer 3

80 J

Question 4

A 50.0-kg (including the passenger)sled is subject to a net force of 10.0 N pushing in the direction of the sled's motion as it is moving over a horizontal surface for a distance of 10.0 m after having started from rest.At this point the sled is released as it starts down a 10.0° incline.However,the snow is not very deep,and the sled stops after having moved an additional 25.0 m.What is the work done by friction while the sled is on the incline?

A) -2170.6 J
B) -2270.6 J
C) -2070.6 J
D) -12410.1 J
E) ​-12210.1 J

Question 5

If during a given physical process the only force acting on an object is friction,which of the following must be assumed in regard to the object's kinetic energy?

A) It decreases.
B) It increases.
C) It remains constant.
D) It cannot be determined from the information given.

Question 6

A horizontal force of 200 N is applied to a 55-kg cart across a 15-m level surface.If the cart accelerates at 2.0 m/s²,then what is the work done by the force of friction as it acts to retard the motion of the cart?

A) -4650 J
B) -1350 J
C) -3000 J
D) -90 J
E) ​-310 J

Question 7

I use a rope 4.00 m long to swing a 8.0-kg weight around my head.The tension in the rope is 28.0 N.In half a revolution how much work is done by the rope on the weight?

A) 112 J
B) 896 J
C) 56 J
D) 0
E) ​14 J

Question 8

A 15.00-kg bowling ball falls from a 3.00-m shelf.Just before hitting the floor,what will be its kinetic energy? (g = 9.80 m/s² and assume air resistance is negligible)

A) 450 J
B) 68 J
C) 5 J
D) 441 J
E) ​45 J

Question 9

A horizontal force of 81 N is applied to move a 47-kg cart across a 7.0-m level surface.What work is done by the 81-N force?

A) 12.06 J
B) 26649 J
C) 567 J
D) 543.86 J
E) ​0.25 J

Question 10

The work done by static friction can be:

A) positive.
B) negative.
C) zero.
D) Any of the above.

Question 11

What is the kinetic energy of a 0.155-kg baseball thrown at 50.0 m/s (112 mph)?

A) 387.5 J
B) 3.875 J
C) 193.75 J
D) 7.75 J
E) ​0.005 J

Question 12

If both mass and velocity of a ball are tripled,the kinetic energy is increased by a factor of:

A) 3.
B) 6.
C) 9.
D) 27.

Question 13

A very light cart holding a 200-N box is moved at constant velocity across a 20-m level surface.What is the net work done in the process?

A) zero
B) 1/10 J
C) 10 J
D) 100 J
E) ​4000 J

Question 14

Which of the following is an example of a nonconservative force?

A) gravity
B) magnetism
C) friction
D) Both choices A and B are valid.

Question 15

A 1,200-kg automobile moving at 29 m/s has the brakes applied with a deceleration of 3.0 m/s².How far does the car travel before it stops?

A) 140 m
B) 280 m
C) 504600 m
D) 31200 m
E) ​400 m

Question 16

Which of the following is that form of energy associated with an object's location in a conservative force field?

A) potential
B) thermal
C) bio-chemical
D) kinetic

Question 17

Rupel pushes a box 3.00 m by applying a 19.0-N horizontal force.What work does she do?

A) 6.33 J
B) 0.16 J
C) 57 J
D) -57 J
E) ​19 J

Question 18

The unit of work,joule,is dimensionally the same as:

A) newton/second.
B) newton/kilogram.
C) newton-second.
D) newton-meter.

Question 19

A golf ball hits a wall and bounces back at 1/3 the original speed.What part of the original kinetic energy of the ball did it lose in the collision?

A) 2/3
B) 1/6
C) 8/9
D) 1/9
E) ​1/3

Question 20

Which of the following is that form of energy associated with an object's motion?

A) potential
B) thermal
C) bio-chemical
D) kinetic

Question 21

A baseball outfielder throws a baseball of mass 0.20 kg at a speed of 50 m/s and initial angle of 30°.What is the kinetic energy of the baseball at the highest point of the trajectory? Ignore air friction.

A) zero
B) 375 J
C) 188 J
D) 62 J
E) ​250 J

Question 22

When an object is dropped from a tower,what is the effect of the air resistance as it falls?

A) does positive work
B) increases the object's kinetic energy
C) increases the object's potential energy
D) None of the above choices are valid.

Question 23

A 13.0-kg box starts at rest and slides 3.5 m down a ramp inclined at an angle of 10° with the horizontal.If there is no friction between the ramp surface and crate,what is the velocity of the crate at the bottom of the ramp? (g = 9.8 m/s²)

A) 11.91 m/s
B) 3.45 m/s
C) 8.28 m/s
D) 8.22 m/s
E) ​68.6 m/s

Question 24

A simple pendulum,3.0 m in length,is released with a push when the support string is at an angle of 20° from the vertical.If the initial speed of the suspended mass is 1.3 m/s when at the release point,what is its speed at the bottom of the swing? (g = 9.8 m/s²)

A) 2.3 m/s
B) 1.9 m/s
C) 6.4 m/s
D) 5.2 m/s
E) ​7.8 m/s

Question 25

A pole vaulter clears 4.00 m.With what speed does he strike the mat in the landing area?

A) 78.4 m/s
B) 6.3 m/s
C) 8.9 m/s
D) 4.4 m/s
E) ​0.2 m/s

Question 26

A hill is 200 m long and makes an angle of 12° with the horizontal.As a 65-kg jogger runs up the hill,how much work does gravity do on the jogger?

A) 127,400 J
B) 26,488 J
C) −26,488 J
D) ​124,616 J
E) ​zero

Question 27

Samantha pushes a 50-N crate up a ramp 25 m in length and inclined at 10° with the horizontal.What potential energy change does the crate experience?

A) 1,231 J
B) 1,250 J
C) 12 J
D) 217 J
E) ​7,198 J

Question 28

A baseball catcher puts on an exhibition by catching a 0.10-kg ball dropped from a helicopter at a height of 81 m.What is the speed of the ball just before it hits the catcher's glove 1 m above the ground? (g = 9.8 m/s² and ignore air resistance)

A) 39.6 m/s
B) 0.05 m/s
C) 1568 m/s
D) 28 m/s
E) ​40.09 m/s

Question 29

An 80,000-kg airliner is flying at 900 km/h at a height of 10.0 km.What is its total energy (kinetic + potential)if the total was 0 when the airliner was at rest on the ground?

A) 40,240 MJ
B) 32,408 MJ
C) 7,850 MJ
D) zero
E) ​10,340 MJ

Question 30

A 1.00-kg ball has zero potential and kinetic energy.Maria drops the ball into a 10.00-m-deep well.After the ball comes to a stop in the mud,the sum of its potential and kinetic energy is:

A) zero.
B) 98 J.
C) −98 J.
D) 196 J.
E) ​- 196 J.

Question 31

A rock is thrown straight up with an initial velocity of 14 m/s.Ignore energy lost to air friction.How high will the rock rise?

A) 7 m
B) 98 m
C) 20 m
D) 10 m
E) ​0.1 m

Question 32

Old Faithful geyser in Yellowstone Park shoots water hourly to a height of 30 m.With what velocity does the water leave the ground?

A) 12 m/s
B) 17 m/s
C) 20 m/s
D) 24 m/s
E) ​588 m/s

Question 33

What is the minimum amount of energy required for an 60-kg climber carrying a 5-kg pack to climb Mt.Everest,8,150 m high?

A) 5.19 MJ
B) 4.39 MJ
C) 4.79 MJ
D) 0.53 MJ
E) ​0.45 MJ

Question 34

A 1.00-kg ball has zero kinetic and potential energy.Ernie drops the ball into a 10.0-m-deep well.Just before the ball hits the bottom,the sum of its kinetic and potential energy is:

A) zero.
B) 98 J.
C) −98 J.
D) 196 J.
E) ​- 196 J.

Question 35

A professional skier reaches a speed of 55 m/s on a 30° ski slope.Ignoring friction,what was the minimum distance along the slope the skier would have had to travel,starting from rest?
​

A) 154.34 m
B) 178.22 m
C) 308.67 m
D) 5.61 m
E) ​0.003 m

Question 36

As an object is lowered into a deep hole in the surface of the earth,which of the following must be assumed in regard to its potential energy?

A) increase
B) decrease
C) remain constant
D) cannot tell from the information given

Question 37

A simple pendulum,1.00 m in length,is released from rest when the support string is at an angle of 20.0° from the vertical.What is the speed of the suspended mass at the bottom of the swing? (g = 9.80 m/s² and ignore air resistance)

A) 4.43 m/s
B) 2.59 m/s
C) 1.18 m/s
D) 1.09 m/s
E) ​0.3 m/s

Question 38

Two blocks are released from the top of a building.One falls straight down while the other slides down a smooth ramp.If all friction is ignored,which one is moving faster when it reaches the bottom?

A) The block that went straight down.
B) The block that went down the ramp.
C) They both will have the same speed.
D) Insufficient information to work the problem.

Question 39

A simple pendulum,2.0 m in length,is released by a push when the support string is at an angle of 25° from the vertical.If the initial speed of the suspended mass is 1.3 m/s when at the release point,to what maximum angle will it move in the second half of its swing?

A) 37°
B) 30°
C) 27°
D) 21°
E) ​180°

Question 40

A 20.0-kg crate,initially at rest,slides down a ramp 2.0 m long and inclined at an angle of 20° with the horizontal.If there is no friction between ramp surface and crate,what is the kinetic energy of the crate at the bottom of the ramp? (g = 9.8 m/s²)

A) 368 J
B) 392 J
C) 268J
D) 134 J
E) ​67 J

Question 41

A baseball catcher puts on an exhibition by catching a 0.170-kg ball dropped from a helicopter at a height of 110 m above the catcher.If the catcher "gives" with the ball for a distance of 0.695 m while catching it,what average force is exerted on the mitt by the ball? (g = 9.80 m/s²)

A) 27 N
B) 183 N
C) 264 N
D) 274 N
E) ​749 N

Question 42

A Hooke's law spring is mounted horizontally over a frictionless surface.The spring is then compressed a distance d and is used to launch a mass m along the frictionless surface.What compression of the spring would result in the mass attaining double the speed received in the above situation?

A) 1.41 d
B) 1.73 d
C) 2.00 d
D) 4.00 d

Question 43

A Hooke's law spring is compressed a distance d and is used to launch a mass m vertically to a height h above its starting position.Under the same compression d,the spring is now used to launch a mass of 2m.How high does this second mass rise?

A) h
B) h/2
C) h/1.41
D) h/4

Question 44

A girl and her bicycle have a total mass of 42 kg.At the top of the hill her speed is 5.0 m/s.The hill is 10 m high and 100 m long.If the force of friction as she rides down the hill is 25 N,what is her speed at the bottom?

A) 5.0 m/s
B) 12.1 m/s
C) 10.1 m/s
D) 46.3 m/s
E) ​She stops before she reaches the bottom.

Question 45

A bobsled makes a run down an ice track starting at 150 m vertical distance up the hill.If there is no friction,what is the velocity at the bottom of the hill?

A) 27 m/s
B) 38 m/s
C) 36 m/s
D) 54 m/s
E) ​45 m/s

Question 46

By how much is the energy stored in a Hooke's law spring increased when its stretch is increased from 6.00 cm to 15.00 cm?

A) 325%
B) 425%
C) 525%
D) 625%
E) ​The correct answer is not given.

Question 47

An amount of work equal to 2.5 J is required to compress the spring in a spring-gun.What is the "launch speed" of a 25-g marble?

A) 14 m/s
B) 15 m/s
C) 10 m/s
D) 4 m/s
E) ​0.45 m/s

Question 48

A parachutist of mass 52.0 kg jumps out of an airplane at a height of 1 080 m.The parachute deploys,and she lands on the ground with a speed of 6.0 m /s.How much energy was lost to air friction during this jump?

A) 550 000 J
B) 191 000 J
C) 548 000 J
D) 549 000 J
E) ​559 000 J

Question 49

A girl and her bicycle have a total mass of 43.0 kg.At the top of the hill her speed is 5.0 m/s,and her speed doubles as she rides down the hill.The hill is 15.0 m high and 100 m long.How much kinetic energy and potential energy is lost to friction?

A) 4,709 J
B) 6,859 J
C) 4,171 J
D) 4,809 J
E) ​4,609 J

Question 50

A Hooke's law spring is mounted horizontally over a frictionless surface.The spring is then compressed a distance d and is used to launch a mass m along the frictionless surface.What compression of the spring would result in the mass attaining double the kinetic energy received in the above situation?

A) 1.41 d
B) 1.73 d
C) 2.00 d
D) 4.00 d

Question 51

A pile driver drives a post into the ground.The mass of the pile driver is 2,700 kg and it is dropped through a height of 8.0 m on each stroke.If the resisting force of the ground is 3.0 × 10⁶ N,how far is the post driven in on each stroke?

A) 7.1 cm
B) 0.7 cm
C) 0.1 cm
D) 63.5 cm
E) ​8.1 cm

Question 52

A 2,000-kg ore car rolls 50.0 m down a frictionless 10.0° incline.If there is a horizontal spring at the end of the incline,what spring constant is required to stop the ore car in a distance of 1.00 m?

A) 347 kN/m
B) 334 kN/m
C) 1969 kN/m
D) 174 kN/m
E) 87​ kN/m

Question 53

I drop a 65-g golf ball from 3.0 m high.It rebounds to 1.0 m.How much energy is lost?

A) 1.27 J
B) 12.74 J
C) 1.32 J
D) 1.22 J
E) ​0

Question 54

A Hooke's law spring is compressed 15.0 cm from equilibrium,and the potential energy stored is 73.0 J.What compression (as measured from equilibrium)would result in 100 J being stored in this case?

A) 12.4 cm
B) 17.6 cm
C) 45.3 cm
D) ​35.2 cm
E) ​No answer is correct.

Question 55

A Hooke's law spring is compressed 12.0 cm from equilibrium and the potential energy stored is 72.0 J.What is the spring constant in this case?

A) 10000 N/m
B) 5000 N/m
C) 100 N/m
D) ​1 N/m
E) ​No answer is correct.

Question 56

A 24-N crate starting at rest slides down a rough 4-m long ramp,inclined at 29° with the horizontal.20 J of energy is lost to friction.What will be the speed of the crate at the bottom of the incline?

A) 11.4 m/s
B) 3.3 m/s
C) 1.5 m/s
D) 4.7 m/s
E) ​21.6 m/s

Question 57

The SI units for k,the spring constant,are equivalent to:

A) J.
B) J / N.
C) kg / s².
D) None of the above.

Question 58

Adisa pulls a 40-N crate up a 6.0-m long inclined plane at a constant velocity.If the plane is inclined at an angle of 38° to the horizontal and there is a constant force of friction of 10 N between the crate and the surface,what is the net change in potential energy of the crate?

A) 148 J
B) −148 J
C) 189 J
D) −189 J
E) ​None of these

Question 59

Preston pushes a wheelbarrow weighing 490 N to the top of a 45.0-m ramp,inclined at 20.0° with the horizontal,and leaves it.Tamara accidentally bumps the wheelbarrow.It slides back down the ramp,during which an 80.0-N frictional force acts on it over the 45.0 m.What is the wheelbarrow's kinetic energy at the bottom at of the ramp? (g = 9.8 m/s²)

A) 3,942 J
B) 17,120 J
C) 11,142 J
D) 7,542 J
E) ​1,231 J

Question 60

A 40-N crate is pulled up a 4-m inclined plane by a worker at constant velocity.If the plane is inclined at an angle of 37° to the horizontal and there exists a constant frictional force of 10 N between the crate and the surface,what is the force applied by the worker?

A) zero
B) 14 N
C) 24 N
D) 34 N
E) ​136 N

Question 61

A 100-W light bulb is left on for 10.0 hours.Over this period of time,how much energy was used by the bulb?

A) 1 000 J
B) 360 000 J
C) 3 600 000 J
D) 1.34 hp
E) ​36 000 J

Question 62

A jet engine develops 1.1 × 10⁵ N of thrust in moving an airplane forward at a speed of 850 km/h.What is the power developed by the engine?

A) 935 kW
B) 259.7 MW
C) 26 MW
D) 31 MW
E) ​21 MW

Question 63

The unit of power,watt,is dimensionally the same as:

A) joule-second.
B) joule/second.
C) joule-meter.
D) joule/meter.

Question 64

A force of 5.0 N is applied to a 20-kg mass on a horizontal frictionless surface.As the speed of the mass increases at a constant acceleration,the power delivered to it by the force:

A) remains the same.
B) increases.
C) decreases.
D) doubles every 4.0 seconds.

Question 65

The net force acting on a 4.0-kg object is given by F_x = (10 − x)N,where F_x is in newtons and x is in meters.How much work is done on the object as it moves from x = 0 to x = 15 m?

A) 5 J
B) 15 J
C) 37.5 J
D) 18.75 J
E) ​28.125 J

Question 66

A Hooke's law spring is compressed a distance d and is used to launch a particle of mass m vertically to a height h above its starting position.Under double the compression,the spring is now used to launch a particle of mass 2 m.How high does the second mass rise above its starting position?

A) h
B) 2 h
C) 3 h
D) 4 h

Question 67

The area under the force vs.displacement curve represents:

A) area.
B) force.
C) work.
D) coefficient of static friction.

Question 68

A Hooke's law spring is compressed a distance d and is used to launch a mass m vertically to a height h above its starting position.Under double the compression,the spring is now used to launch the mass.How high does the mass now rise above its starting position?

A) 2 h
B) 1.41 h
C) 3 h
D) 4 h

Question 69

The rate at which work is done is equivalent to which of the following?

A) increase in potential energy
B) thermal energy
C) potential energy
D) power

Question 70

A speed boat requires 82 kW to move at a constant speed of 16 m/s.What is the resistive force of the water at this speed?

A) 1 310 N
B) 5 130 N
C) 5 230 N
D) 5 030 N
E) ​1 410 N

Question 71

A 60-kg woman runs up a flight of stairs having a rise of 4.5 m in a time of 4.3 s.What average power did she supply?

A) 63 W
B) 615 W
C) 562 W
D) 625 W
E) ​605 W

Question 72

Is it possible for the total mechanical energy of a moving particle to be negative?

A) No,because a moving particle has positive kinetic energy.
B) No,because potential energy cannot have a value more negative than the value of the positive kinetic energy of the particle.
C) Only if friction is involved.
D) yes

Question 73

A 180-hp engine can deliver,in SI units,an average power of ____.(1 hp = 746 W)

A) 0.24 W
B) 4.14 W
C) 134 300 W
D) 180 W
E) ​926 W

Question 74

The quantity of work equal to one joule is also equivalent to which of the following?

A) watt
B) watt /s
C) watt ⋅ s
D) watt /s²

Question 75

A 1 000-kg sports car accelerates from zero to 28 m/s in 7.0 s.What is the average power delivered by the automobile engine?

A) 112 kW
B) 2 kW
C) 56 kW
D) 196 kW
E) ​66 kW

Question 76

Water flows over a section of Niagara Falls at a rate of 1.20 × 10⁶ kg/s and falls 51.0 m.What is the power dissipated by the waterfall?

A) 599.76 MW
B) 61.2 MW
C) 43 MW
D) 499.76 MW
E) ​699.76 MW

Question 77

An automobile delivers 35.0 hp to its wheels when moving at a constant speed of 21.0 m/s.What is the resistance force on the automobile at this speed? (1 hp = 746 watts)

A) 548 310 N
B) 1 250 N
C) 1 240 N
D) 1 190 N
E) ​450 N

Question 78

The net force acting on a 13.0-kg object is given by F_x = (20 − x)N,where F_x is in newtons and x is in meters.How much work is done on the object as it moves from x = 0 to x = 13 m?

A) 7 J
B) 91 J
C) 175.5 J
D) 149 J
E) ​87.75 J

Question 79

A force of 100 N is applied to a 50-kg mass in the direction of motion for a distance of 6.0 m and then the force is increased to 180 N for the next 4.0 m.For the 10 m of travel,how much work is done by the varying force?

A) 1 320 J
B) 1 480 J
C) 66 000 J
D) 26.4 J
E) ​1 220 J

Question 80

Yuri,a Russian weightlifter,is able to lift 265 kg 2.20 m in 2.10 s.What is his power output?

A) 583.00 W
B) 2.72 kW
C) 1.18 kW
D) 12.00 kW
E) ​27.21 kW