Energy, Work, and Powersharrockclass.weebly.com/uploads/2/7/6/1/2761529/9.0_-_energy.pdf · Energy,...

Chapter 9 Energy

1Doc Fizzix Problem Set • Chapter 9

Name Class Period

© 20

13 Doc F

izzix

Produc

ts, Sa

ving t

he wo

rld w

ith his

knowle

dge of s

cience

Energy, Work, and Power9.1 Work

€

W = Fd

€

W = ΔPE = mgΔh

€

W = ΔKE =mΔv 2

2

1. While driving home from work a monkey runs out of gas. The monkey pushes the car with a 543 N force to the nearest gas station some 218 meters away. How much work does the monkey do pushing the car?

Write the formula(s) are you using

Substitute the known values and solve.

What are the givens and unknowns?

€

W =

€

F =

€

d =

a)

2. How much work is done to raise a 1-kg hamburger, 0.3 meters, from the table to your mouth?




€

W =

€

F =

€

d =

a)

Chapter 9 Energy


Name Class Period

© 20

13 Doc F

izzix

Produc

ts, Sa

ving t

he wo

rld w

ith his

knowle

dge of s

cience

3. A 60-kg monkey climbs a 4-m high flight of stairs in the main mall at Mc Neil High School. How much work does the monkey do?




€

W =

€

F =

€

d =

a)

4. A 900-N crate is at rest on the floor. a) How much work is required to pull the crate 6.0-m across the floor if the force of friction acting against the crate is 180 N? b) How much work is required to lift the same crate 6.0 meters vertically?




€

W =

€

F =

€

d =

a) b)

Chapter 9 Energy


Name Class Period

© 20

13 Doc F

izzix

Produc

ts, Sa

ving t

he wo

rld w

ith his

knowle

dge of s

cience

9.2 Potential Energy

€

PE = mgh

€

W = ΔPE = mgΔh

5. How high will a 0.325-kg ball travel if thrown straight up by a monkey who does 115-J of work on the ball?



€

W =

€

ΔPE =

€

m =

€

g =

€

h =


a)

6. The average food energy intake for humans is 2000 Calories/day. One dietary Calorie is equivalent to 4186 J. How high would a 120 lb (54.43-kg) person have to climb in order to “burn off” all the calories they consume in one day?



€

W =

€

ΔPE =

€

m =

€

g =

€

h =


a)

Chapter 9 Energy


Name Class Period

© 20

13 Doc F

izzix

Produc

ts, Sa

ving t

he wo

rld w

ith his

knowle

dge of s

cience

7. A monkey places a 2.0-kg hammer on the edge of a table 0.40-m above the floor. If the hammer should fall and just by chance land on the top of a loose nail, how much work would the hammer do to the nail?



€

W =

€

ΔPE =

€

m =

€

g =

€

h =


a)

Chapter 9 Energy


Name Class Period

© 20

13 Doc F

izzix

Produc

ts, Sa

ving t

he wo

rld w

ith his

knowle

dge of s

cience

9.3 Kinetic Energy

€

KE =mv 2

2

€

W = ΔKE =mΔv 2

2

8. a) What is the kinetic energy of a 3,000-pound (1,361-kg) Porsche driven by a monkey, traveling at 40 mph (17.88 m/s)? b) What is the kinetic energy if the speed of the car is doubled to 80 mph (35.76 m/s)?




€

KE =

€

m =

€

v =

a) b)

9. Assume your mass is 150-pounds (68.03-kg). How fast would you have to run in order to have the same kinetic energy as a 3,000-pound (1,361-kg) Porsche driven by a monkey traveling 55 mph (24.59 m/s)?




€

KE =

€

m =

€

v =

a)

Chapter 9 Energy


Name Class Period

© 20

13 Doc F

izzix

Produc

ts, Sa

ving t

he wo

rld w

ith his

knowle

dge of s

cience

10. Jamaican sprinter Usain Bolt shocked the world by running the 100-meter dash in 9.58 seconds. Determine Usain’s kinetic energy if his weight was 190 lbs (86 kg).




€

KE =

€

m =

€

v =

a)

Chapter 9 Energy


Name Class Period

© 20

13 Doc F

izzix

Produc

ts, Sa

ving t

he wo

rld w

ith his

knowle

dge of s

cience

9.4 Conservation of Energy

€

Ei = E f PEi + KEi = PE f + KE f +W

11. A pendulum is made from a 7.50-kilogram mass attached to a rope connected to the ceiling of a gymnasium. The mass is pushed to the side until it is at position A, 1.5 meters higher than its equilibrium position. After it is released from rest at position A, the pendulum moves freely back and forth between positions A and B, as shown in the diagram below.

What is the total amount of kinetic energy that the mass has as it swings freely through its equilibrium position? [Neglect friction.]



€

PEo =

€

KEo =

€

PE f =

€

KE f =


a)

Chapter 9 Energy


Name Class Period

© 20

13 Doc F

izzix

Produc

ts, Sa

ving t

he wo

rld w

ith his

knowle

dge of s

cience

12. A monkey does 0.20 joule of work to compress the spring in a pop-up toy. If the mass of the toy is 0.010 kilogram, a) what is the maximum vertical height that the toy can reach after the spring is released? b) How fast was the toy traveling when it left the table?



€

PEo =

€

KEo =

€

PE f =

€

KE f =


a) b)

Chapter 9 Energy


Name Class Period

© 20

13 Doc F

izzix

Produc

ts, Sa

ving t

he wo

rld w

ith his

knowle

dge of s

cience

13. A baseball pitcher can throw a baseball at 100 mph (44.70 m/s). If such a pitch had been directed vertically upwards how height would it have traveled?



€

PEo =

€

KEo =

€

PE f =

€

KE f =


a)

14. A 15-m rope is hanging form a tree branch to the ground. A monkey runs as fast as it can towards the rope and grab a hold of it. After grabbing the rope, the monkey raises 2-m above the ground. How fast was the monkey running when he grabbed the rope?



€

PEo =

€

KEo =

€

PE f =

€

KE f =


a)

Chapter 9 Energy


Name Class Period

© 20

13 Doc F

izzix

Produc

ts, Sa

ving t

he wo

rld w

ith his

knowle

dge of s

cience

15. A ball starts from rest and rolls down a hill. The height of the hill is not known but when the ball is 3 meters above the ground it is moving at 5 m/s. a) What is the total mechanical energy of the ball? b) What was the height of the hill?



€

PEo =

€

KEo =

€

PE f =

€

KE f =


a) b)

16. A monkey throws a banana from the roof of a 99-ft (30-m) building with an initial speed of 10 m/s. a) How much mechanical energy does the banana have on release and b) what is the speed of the banana as it hits the ground? Dam monkey



€

PEo =

€

KEo =

€

PE f =

€

KE f =


a) b)

Chapter 9 Energy


Name Class Period

© 20

13 Doc F

izzix

Produc

ts, Sa

ving t

he wo

rld w

ith his

knowle

dge of s

cience

17. An 80-g (0.08-gk) arrow is fired from a bow whose string exerts an average force of 95 N on the arrow over an 80-cm (0.8 m) distance. What is the speed of the arrow as it leaves the bow?




€

W =

€

ΔKE =

a)

18. A 4-kg block is sitting at rest on a friction free tabletop. A monkey pushes the block along the table and after the block has moved 8-m, the monkey stops pushing on the block. At the point the monkey releases the block, the block is traveling at 10-m/s, a) how much mechanical energy does the block have and b) how large was the force applied by the monkey?




€

W =

€

ΔKE =

a) b)

Chapter 9 Energy


Name Class Period

© 20

13 Doc F

izzix

Produc

ts, Sa

ving t

he wo

rld w

ith his

knowle

dge of s

cience

19. A car traveling at 30 mph (13.41 m/s) slams on the brakes in order to avoid an accident. It takes 45.93 ft (14-m) for the car to come to rest. a. What will be the stopping distance if the velocity is doubled (60 mph)? b. What will be the stopping distance if the velocity is tripled (90 mph)?c. What will be the stopping distance if the velocity is if quadrupled (120 mph)?

20. The diagram below represents a 155-newton box on a ramp. Applied force F causes the box to slide from point A to point B.

What is the total amount of gravitational potential energy gained by the box?



€

PEo =

€

KEo =

€

PE f =

€

KE f =


a)

Chapter 9 Energy


Name Class Period

© 20

13 Doc F

izzix

Produc

ts, Sa

ving t

he wo

rld w

ith his

knowle

dge of s

cience

21. Frank, a San Francisco hot dog vender, has fallen asleep on the job. When an earthquake strikes, his 300-kg hot-dog cart rolls down a hill and then up another. When the cart reaches the top of the hill at point A, its speed is 8.00 m/s. a) How fast is the hot-dog cart going when it goes up the next hill at point B? b) What is the total mechanical energy at point B?



€

PEo =

€

KEo =

€

PE f =

€

KE f =


a) b)

Chapter 9 Energy


Name Class Period

© 20

13 Doc F

izzix

Produc

ts, Sa

ving t

he wo

rld w

ith his

knowle

dge of s

cience

22. An 800 kg rollercoaster had a potential energy of 588,240 J at the top of the first hill. What is the maximum height of the next hill on the track so that the rollercoaster can make it to the top if 20,000 J of work is done to overcome friction along the way?



€

PEo =

€

KEo =

€

PE f =

€

KE f =

€

W =


a)

23. A motor is used as an elevator to lift a 10 N monkey to a height of 4.5-meters. If the total amount of energy used by the motor is 60 J, how much energy was converted to heat and sound?



€

PEo =

€

KEo =

€

PE f =

€

KE f =

€

W =


a)

Chapter 9 Energy


Name Class Period

© 20

13 Doc F

izzix

Produc

ts, Sa

ving t

he wo

rld w

ith his

knowle

dge of s

cience

24. A motor lift a 5 N mass to a height of 3.5-meters. If the total amount of energy used by the motor is 35 J, how much energy was converted to heat and sound?



€

PEo =

€

KEo =

€

PE f =

€

KE f =

€

W =


a)

Chapter 9 Energy


Name Class Period

© 20

13 Doc F

izzix

Produc

ts, Sa

ving t

he wo

rld w

ith his

knowle

dge of s

cience

25. A block weighing 40-newtons is released from rest on an incline 8.0 meters above the horizontal, as shown in the diagram below.

If 50-joules of heat is generated as the block slides down the incline, what is the maximum kinetic energy of the block at the bottom of the incline?



€

PEo =

€

KEo =

€

PE f =

€

KE f =

€

W =


a)

Chapter 9 Energy


Name Class Period

© 20

13 Doc F

izzix

Produc

ts, Sa

ving t

he wo

rld w

ith his

knowle

dge of s

cience

26. A 30-kg monkey is sliding down a playground slide that is 2.5-m high. The monkey comes to the bottom of the slide with a speed of 2.0 m/s. How much energy was dissipated as heat?



€

PEo =

€

KEo =

€

PE f =

€

KE f =

€

W =


a)

Chapter 9 Energy


Name Class Period

© 20

13 Doc F

izzix

Produc

ts, Sa

ving t

he wo

rld w

ith his

knowle

dge of s

cience

9.5 Springs

€

PE =12

kx 2

27. How much energy is stored in a spring with a spring constant of 50N/m when it is compressed 0.05 m?




€

PEs =

€

k =

€

Δx =

a)

28. A dart of mass 0.10 kg is pressed into a toy dart gun. The spring is compressed 6.0 cm and has a spring constant of 250 N/m. What is the speed of the dart after the gun is fired?




€

PEs =

€

ΔKE =

a)

Chapter 9 Energy


Name Class Period

© 20

13 Doc F

izzix

Produc

ts, Sa

ving t

he wo

rld w

ith his

knowle

dge of s

cience

29. A toy car has a mass of 2.5-kg. The car is moving along the floor at 2.0 m/s when it hits a spring attached to a wall. The spring has a spring constant of 32 N/m. How far will the spring be compressed in collision with the toy car?




€

PEs =

€

ΔKE =

a)

30. A 0.01 kg steel ball is loaded into a spring gun pointed straight up. When the spring is compressed .10 m, the ball reaches a height of 20 meters above the gun. a) How much energy was stored in the spring gun and b) what is the spring constant of the gun?




€

PEs =

€

ΔPE =

a) b)

Chapter 9 Energy


Name Class Period

© 20

13 Doc F

izzix

Produc

ts, Sa

ving t

he wo

rld w

ith his

knowle

dge of s

cience

9.6 Power

€

P =Wt

P =ΔEt

31. A 51-kg monkey climbs a 6-m tall tree in 10-s, how much work does the monkey do and what is the power output of the monkey?




€

P =

€

W =

€

ΔPE =

€

t =

a) b)

32. A small electric motor is used to lift a 0.50-kilogram mass at constant speed. If the mass is lifted a vertical distance of 1.5 meters in 5.0 seconds, what is the average power developed by the motor?




€

P =

€

W =

€

ΔPE =

€

t =

a)

Chapter 9 Energy


Name Class Period

© 20

13 Doc F

izzix

Produc

ts, Sa

ving t

he wo

rld w

ith his

knowle

dge of s

cience

33. A monkey puts out 50-W of power for 1.0-hour, how much work does the monkey do?




€

P =

€

W =

€

t =

a)

34. An 8-kg mass is lifted from the ground using a power of 25-W in 7-seconds. To what height was the mass lifted?




€

P =

€

W =

€

ΔPE =

€

t =

a)

Chapter 9 Energy


Name Class Period

© 20

13 Doc F

izzix

Produc

ts, Sa

ving t

he wo

rld w

ith his

knowle

dge of s

cience

35. A net force of 25-newtons is applied to a moving cart for 10 seconds and the cart travels 5 meters. What was the power delivered to the cart?




€

P =

€

W =

€

t =

a)

36. A 3,000-pound (1,361-kg) Porsche is at rest and pointed north when the gas pedal is pressed to the metal. If the car goes from 0-60 mph (26.82 m/s) in 3.7 seconds, calculate the a) change in kinetic energy and the b) power output?




€

P =

€

W =

€

ΔKE =

€

t =

a) b)

Chapter 9 Energy


Name Class Period

© 20

13 Doc F

izzix

Produc

ts, Sa

ving t

he wo

rld w

ith his

knowle

dge of s

cience

37. A monkey has bought a piano but lives on the sixth-story (16.0-m) of an apartment building and needs to get the piano to his flat. The piano will not fit through the doors into the apartment but will fit through the outside window. The monkey attaches a rope to the piano and the other end to a 1,750-W motor attached to the top of the building. How long will it take to lift the 285-kg piano to the monkey’s flat?




€

P =

€

W =

€

ΔPE =

€

t =

a)

Energy, Work, and Powersharrockclass.weebly.com/uploads/2/7/6/1/2761529/9.0_-_energy.pdf · Energy,...

Documents

Transcript of Energy, Work, and Powersharrockclass.weebly.com/uploads/2/7/6/1/2761529/9.0_-_energy.pdf · Energy,...