Slide 1 / 38 Slide 2 / 38 1 A student throws a ball upward where - - PDF document

SLIDE 1

Slide 1 / 38 AP Physics C Work And Energy Without Calculus Slide 2 / 38

1 A student throws a ball upward where the initial potential energy is 0. At a height of 15 meters the ball has a potential energy of 60 joules and is moving upward with a kinetic energy of 40 joules. Ignoring air resistance, the maximum height achieved by the ball is most nearly

A 10 m B

20 m

C

25 m

D

30 m

E

40 m

Slide 3 / 38

2 A box of mass m is lifted a vertical distance h in time t with a constant velocity. The power supplied by the lifting force is approximately

A mght B

mgh/t

C

zero

D

mgt/h

E

mg/ht

Slide 4 / 38

3 A crate is lifted by a force F which is greater in magnitude than the crate’s weight W. The change in kinetic energy of the crate during this time is equal to the

A work done by the net force (F W) B work done by F C

work done by W

D

the change in momentum of the rock before and after this time

E

the change in the potential energy of the rock before and after this time.

Slide 5 / 38

4 A constant force supplies an average power of 8 watts to a box during a certain time interval. If the box has an average speed of 4 meters per second and the force acts in the same direction as motion

• f the object, the magnitude of the force is

A 8 N B

6 N

C

4 N

D

2N

E

1N

Slide 6 / 38

5 A pencil is moved from point A to point B along a curved path. The work done by the gravitational force on the pencil depends on which of the following:

A the velocity of the object

as it moves between A and B

B

the positions of points A and B

C

the path taken between A and B

D

both the positions of A and B and the path taken between them

E

the nature of the external force that moves the object from A to B

SLIDE 2

Slide 7 / 38

6 A man lifts a mass m at constant speed to a height h in time t. How much work is done by the man?

A mgt B

zero

C

mgh

D

mgh/t

E

cannot be determined

Slide 8 / 38

7 A 3 m long frictionless pendulum of swings with an amplitude of 10°. At its equilibrium position the kinetic energy of the pendulum is 20 J. What is the potential energy of the pendulum when the kinetic energy is 5 J?

A

3.3 J

B

5 J

C

6.7 J

D

10 J

E

15 J

Slide 9 / 38

8 On top of a 300meterhigh skyscraper, a 2kilogram ball is thrown directly downward with an initial speed of 20 meters per second. If the ball reaches the ground with a speed of 60 meters per second, the energy lost to friction is approximately

A 0J B

1800 J

C

2300 J

D

2800 J

E

3300 J

Slide 10 / 38

9 A spring has a spring constant of 100 N/m and is 0.1 m long when unstretched. One end is attached to a center post that is free to rotate on a frictionless table

• top. The other end is attached to 2 kg disc moving in

uniform circular motion, which stretches the spring by 0.05 m. What is the centripetal force on the disc?

A 0.5 N B

5 N

C

10 N

D

500 N

E

1,000 N

Slide 11 / 38

10 A spring has a spring constant of 100 N/m and is 0.1 m long when unstretched. One end is attached to a center post that is free to rotate on a frictionless table top. The other end is attached to 2 kg disc moving in uniform circular motion, which stretches the spring by 0.05 m. What is the work done on the disc by the spring during one full circle?

A 0 J B

0.5 J

C

186 J

D

314 J

E

628 J

Slide 12 / 38

11 A student pushes a box across a rough, flat surface at a constant speed of 1 meter per second. The box has a mass of 50 kilograms and the coefficient of sliding friction is 0.2. The power supplied by the student to the box is

A 0 B

5 W

C

50 W

D

100 W

E

200 W

SLIDE 3

Slide 13 / 38

12 A ball of mass m is suspended at the end of a massless string of length L as shown below. This pendulum is lifted to a 45o with the verticle and

• released. At the low point of its swing, the speed of

the ball is

A √(gL) B

√(2gL)

C

√((2 - √2)gL)

D

gL

E

(1/2)gL

L

Slide 14 / 38

13 An ideal massless spring is fixed to a wall at one end and attached to a block of mass M on the

• ther end. The spring oscillates with amplitude A
• n a frictionless, horizontal surface. The

maxixmum speed of the block is vm. The spring constant of the spring is

A Mg/A B

Mg/2A

C

Mvm

2/2A

D

Mvm

2/A2

E

Mvm

2/2A2

Slide 15 / 38

14 When the object of mass m1 descends to a distance h, the potential energy of the system decreases by

A

(m1 – m2)gh

B

m1gh

C

(m1 + m2)gh

D

½(m1 + m2)gh

E

M1 M2

Slide 16 / 38

15 A cart of mass M travels along roller coaster that is shown

• above. It consists of a frictionless ramp of height 4R

connected to a frictionless loop of diameter 2R and a frictionless hill of height R. After the hill it comes to a frictionless horizontal track collides with a spring with a force constant K that is attached to the wall. After the collision with the spring the cart compresses the spring and stops at point E. At which point is the potential energy of the cart the greatest? A Point A B Point B C Point C D Point D E Point E

Slide 17 / 38

16 A cart of mass M travels along roller coaster that is shown

• above. It consists of a frictionless ramp of height 4R

connected to a frictionless loop of diameter 2R and a frictionless hill of height R. After the hill it comes to a frictionless horizontal track collides with a spring with a force constant K that is attached to the wall. After the collision with the spring the cart compresses the spring and stops at point E. At which point is the kinetic energy of the cart the greatest? A Point A B Point B C Point C D Point D E Point E

Slide 18 / 38

17 A cart of mass M travels along roller coaster that is shown

• above. It consists of a frictionless ramp of height 4R

connected to a frictionless loop of diameter 2R and a frictionless hill of height R. After the hill it comes to a frictionless horizontal track collides with a spring with a force constant K that is attached to the wall. After the collision with the spring the cart compresses the spring and stops at point E. How fast is the cart traveling at Point D? A √(2gR) B 2√(2gR) C √(3gR/2) D √(6gR) E 2√(gR)

SLIDE 4

Slide 19 / 38

18 A cart of mass M travels along roller coaster that is shown

• above. It consists of a frictionless ramp of height 4R

connected to a frictionless loop of diameter 2R and a frictionless hill of height R. After the hill it comes to a frictionless horizontal track collides with a spring with a force constant K that is attached to the wall. After the collision with the spring the cart compresses the spring and stops at point E. At Point C what is the direction of the cart's acceleration? A B C D E None

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19 A cart of mass M travels along roller coaster that is shown

• above. It consists of a frictionless ramp of height 4R

connected to a frictionless loop of diameter 2R and a frictionless hill of height R. After the hill it comes to a frictionless horizontal track collides with a spring with a force constant K that is attached to the wall. After the collision with the spring the cart compresses the spring and stops at point E. Determine the cart's acceleration at Point C. A 0.25 g B 2 g C 3 g D 4 g E None

Slide 21 / 38

20 A cart of mass M travels along roller coaster that is shown

• above. It consists of a frictionless ramp of height 4R

connected to a frictionless loop of diameter 2R and a frictionless hill of height R. After the hill it comes to a frictionless horizontal track collides with a spring with a force constant K that is attached to the wall. After the collision with the spring the cart compresses the spring and stops at point E. What is the maximum compression in the spring? A √(2mgR/k) B √(mgR/k) C 2√(mgR/k) D 2√(2mgR/k) E 8mgR/k

Slide 22 / 38

21 A cart of mass M travels along the roller coasters that is shown below. It consists of a frictionless ramp of height 4R connected to a frictionless loop of diameter 2R and a frictionless hill of height R. After the hill it comes to a rough horizontal track. What is the coefficient of kinetic friction so that the cart stops at the end of the rough track? A 0.25 B 0.5 C 1 D 2 E 4

Slide 23 / 38

22 A 5 kilogram block is pushed horizontally across a rough surface with a coefficient of kinetic friction

• f 0.2 by a force F moving at 3 m/s. The work that

is done by the force in 20 seconds is

A 200 J B

400 J

C

600 J

D

800 J

E

1000 J

Slide 24 / 38

23 A ball swings from a simple pendulum in simple harmonic motion as shown below. At which point is the kinetic energy of the ball at its maximum?

A Point 1 B

Point 2

C

Point 3

D

Point 4

E

Point 5

1 2 3 4 5 5 m

SLIDE 5

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24 A ball swings from a simple pendulum in simple harmonic motion as shown below. What happens to the potential energy as the ball passes from point 3 to point 4?

A It increases B

It decreases

C

It stays the same

D

It becomes zero

E

There is not enough information

1 2 3 4 5 5 m

Slide 26 / 38

25 A ball swings from a simple pendulum in simple harmonic motion as shown below. What is the velocity at the pendulum's lowest point?

A 0 m/s B

2 m/s

C

5 m/s

D

8 m/s

E

10 m/s

1 2 3 4 5 5 m

Slide 27 / 38

26 A metal sphere of mass m is tossed from a cliff of height h with an intial velocity vo. What is the total energy of the ball at the top of the cliff?

A 0 B

mgh

C

1/2mvo

2

D

mgh - 1/2mvo

2

E

mgh + 1/2mvo

2

Slide 28 / 38

27 A metal sphere of mass m is tossed from a cliff of height h with an intial velocity vo. What is the total energy of the ball halfway through its fall?

A 0 B

mgh/2

C

1/2mvo

2

D

mgh/2 + 1/2mvo

2

E

mgh + 1/2mvo

2

Slide 29 / 38

28 A metal sphere of mass m is tossed from a cliff of height h with an intial velocity vo. What is the kinetic energy of the ball at the bottom

• f the cliff?

A 0 B

mgh

C

1/2mvo

2

D

mgh - 1/2mvo

2

E

mgh + 1/2mvo

2

Slide 30 / 38

29 A spring gun of spring constant k launches a ball

• f mass m off a cliff of height h. If the velocity of

the ball right before it hits the ground is v, how much was the spring compressed?

A 0 B

mgh

C

(1/2)mv2

D

√(2m(v2/2 - gh)/k)

E

√(2mgh/k)

SLIDE 6

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30 A 10 kg block is raised 5 m at a constant speed of 2 m/s by a crane. The power supplied by the crane is (use g = 10 m/s):

A 200 W B

120 W

C

20 W

D

25 W

E

50 W

Slide 32 / 38

31 A 2-kg mass accerelates 10 m across a frictionless surface by a 40 N force as shown in the figure

• above. The work done over this interval is:

A 120 J B

200√3 J

C

120√3 J

D

120√2 J

E

200 J

Slide 33 / 38

32 An 8 kg mass is attached to a light string 4 m long and hung vertically to make a simple pendulum. The pendulum is displaced until the string is horizontal and then released. What is the approximate speed of the pendulum at its lowest point?

A 5 m/s B

7 m/s

C

9 m/s

D

10 m/s

E

11 m/s

Slide 34 / 38

33 A 60 kg mass is dropped from a roof, which is 5 meters above a spring platform of negligible mass. When the mass lands on the platform, it drops 5 m before it comes to rest. What is the spring constant of the spring?

A 120 N/m B

150 N/m

C

200 N/m

D

240 N/m

E

300 N/m

Slide 35 / 38

34 The graph represents the force exerted on a

• particle. What is the work done on the object from

x=0 to x=4m?

A 8 J B

10 J

C

15 J

D

16 J

E

20 J

Slide 36 / 38

35 What is the work done on the object from x=0 to x=6m?

A 4 J B

6 J

C

10 J

D

12.5 J

E

25 J

SLIDE 7

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36 Which of the following is an accurate statement?

A Potential energy is always negative B

Total energy is always positive

C

During simple harmonic motion, the kinetic energy is always equal to the potential energy

D

Kinetic energy is always positve

E

None of these is true

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