Phys220 Lab#5 - euhv8yewh87vfyw8ov PDF

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Sama Pouri

PHYS 2 220 2000, Purdue University

20 0 21 Feb 23 th, 2

Lab #5 Group me memb mb mbers ers na name me me:: Impul Impulse se an and dL Lin in inear ear Mo Momen men mentum tum Acti Activity vity 1 , P Part art (A (A)) :

Observe the following four videos of the experiments with a two-object system. Two carts (the system consists of both carts) move on a dynamic track: a. Cart A (500 g), moving right at constant 0.37-m/s speed, hits identical cart B (500 g) that is stationary. Cart A stops and cart B starts moving at the speed of 0.37 m/s to the right. https://mediaplayer.pearsoncmg.com/assets/_frames.true/sci-OALG-6-21a b. Cart A loaded with a block (total mass of the cart with the block is 1470 g), and moving right at 0.31 m/s hits stationary cart B (mass 500 g). After the collision, both carts move right: cart B at the speed of 0.47 m/s and cart A at the speed of 0.15 m/s. https://mediaplayer.pearsoncmg.com/assets/_frames.true/sci-OALG-6-2-1b c. Cart A (500 g), with Velcro attached to its front, moves right at 0.31 m/s. Identical cart B (500 g) moves left at constant speed 0.31 m/s. The carts collide, stick together, and stop https://mediaplayer.pearsoncmg.com/assets/_frames.true/sci-OALG-6-2-1c d. Repeat experiment c. but this time cart A is loaded (with a block, total mass is 1470 g) moves right at constant speed of 0.35 m/s. Cart B (500 g) moves left at constant speed of 0.35 m/s. After the collision, both carts stick together and travel right at the speed of 0.17 m/s. https://mediaplayer.pearsoncmg.com/assets/_frames.true/sci-OALG-6-2-1d Fi Filll out the following table for each experiment and determine if anything is the same befor before e an and d afte afterr th the e ccollis ollis ollision ion ion. Does this quantity remain constant in all four experiments. Read and interrogate Observational Experiment Table 6.1 (page 149) in the textbook. Did you come up with the same quantity?

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Sama Pouri

PHYS 2 220 2000, Purdue University

Exper Experimen imen imentt (a) Possible physica physicall qu quantity antity

Mass m

Speed Velocity v

v

Mass times speed mv

Mass times xvelocity component mvx

Cart A (befo befo before re coll collis is ision ion ion) Cart B (befo befo before re coll collis is ision ion ion) Combined physical quantity for Cart A & B (add line 1 and line 2) Cart A (afte afte afterr co colli lli llisi si sion on on) Cart B (afte afte afterr co colli lli llisi si sion on on) Combined physical quantity for Cart A & B (add line 1 and line 2)

Exper Experimen imen imentt (b) Possible physica physicall qua quantity ntity

Mass m

Speed Velocity v

v

Mass times speed mv

Mass times xvelocity component mvx

Cart A (befo befo before re coll collis is ision ion ion) Cart B (befo befo before re coll collis is ision ion ion) Combined physical quantity for Cart A

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Sama Pouri & B (add 1 and line 2)

PHYS 2 220 2000, Purdue University line

Cart A (afte afte afterr co colli lli llisi si sion on on) Cart B (afte afte afterr co colli lli llisi si sion on on) Combined physical quantity for Cart A & B (add line 1 and line 2)

Exper Experimen imen imentt (c (c)) Possible physica physicall qua quantity ntity

Mass m

Speed Velocity v

v

Mass times speed mv

Mass times xvelocity component mvx

Cart A (befo befo before re coll collis is ision ion ion) Cart B (befo befo before re coll collis is ision ion ion) Combined physical quantity for Cart A & B (add line 1 and line 2) Cart A (afte afte afterr co colli lli llisi si sion on on) Cart B (afte afte afterr co colli lli llisi si sion on on) Combined physical quantity for Cart A & B (add line 1 and line 2)

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Sama Pouri

PHYS 2 220 2000, Purdue University

Exper Experimen imen imentt (d) Possible physica physicall qua quantity ntity

Mass m

Speed Velocity v

v

Mass times speed mv

Mass times xvelocity component mvx

Cart A (befo befo before re coll collis is ision ion ion) Cart B (befo befo before re coll collis is ision ion ion) Combined physical quantity for Cart A & B (add line 1 and line 2) Cart A (afte afte afterr co colli lli llisi si sion on on) Cart B (afte afte afterr co colli lli llisi si sion on on) Combined physical quantity for Cart A & B (add line 1 and line 2)

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Sama Pouri

PHYS 2 220 2000, Purdue University

Acti Activity vity 1, Part (B): The initial and final situations for four processes are shown below. Work with your group members to decide which ones are possible according to your knowledge of the physical quantity you came up with. Explain your reasons. The numbers indicate the masses and the speeds of the blocks.

Initial state vi = 0

a.

vf = 1m/s

vi = 0

1 kg spring compressed

2 kg

2 kg

vf = 1m/s

vi = 1m/s

d. 2 kg

vf = 2m/s

2 kg

1 kg

vf = 0

vi = 2m/s 2 kg

1 kg

vi = 1m/s

vi = 1m/s

c.

vf = 1m/s

2 kg

vi = 2m/s

b.

Final state

1 kg

vf = 0

2 kg 1 kg

1 kg

vf = 2m/s

vi = 2m/s

2 kg

1 kg

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vf = 1m/s 1 kg

Sama Pouri

PHYS 2 220 2000, Purdue University

Acti Activity vity 1, Part(c Part(c): ): Suppose that your friend showed you a picture of the experiment that she conducted in her lab (see below). Discuss with your group: Do you believe that this is a real experiment? Why or why not? The left block has three times the mass of the right block.

Acti Activity vity 2 , P Part art art(A (A (A)) : Blocks 1 and 2 rest on a horizontal frictionless surface. A compressed spring of negligible mass separates the blocks. Block 1 has twice the mass of block 2. When the spring is released, the blocks are pushed apart. Work together with your group to answer the questions below concerning this process.

a. Compare the momentum magnitudes of block 1 and of block 2 after the spring is released.

b. Compare the combined momentum of both blocks before the spring is released and the combined momentum after the spring is released.

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Sama Pouri

PHYS 2 220 2000, Purdue University

b. Compare the speed of block 1 to that of block 2 after the spring is released.

d. Together with your group, read Physics Tool box 6.1 in Section 6.4 of the textbook. Represent the process using a qualitative impulse-momentum bar chart for a system consisting of the spring and two blocks. Draw your bar chart on a whiteboard and compare your ideas with another group. Do any other objects exert external forces on the system objects—especially in the horizontal direction?

Acti Activity vity 2, Part (B) (B):: The bar chart on the right represents an impulsemomentum process. Work with your group to answer the following questions concerning this process. a. Describe in words and sketch a physical process that the bar chart might describe. Be specific.

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Sama Pouri

PHYS 2 220 2000, Purdue University

b. Describe what would happen to p 1fx if p2fx was positive three units instead of positive one unit.

Acti Activity vity 3, Part (A): Two equal-mass balls made of different materials swing down at the ends of strings from equal heights and hit identical bricks. Ball 1 bounces back, whereas 3Ball 2 flattens and stops when it hits the brick. Ball 1 knocks the brick over and Ball 2 does not. Work with your group and use your knowledge of impulse-momentum to explain why. Specify the system. Show a bar chart of the process that is consistent with your chosen system.

Acti Activity vity 3, Part(B) Part(B):: Imagine that you drop a ball from a window. After the ball falls 2.0 m, it has acquired considerable speed. Work with your group to answer the following questions: a. Draw a bar chart using the ball and Earth as a system.

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Sama Pouri

PHYS 2 220 2000, Purdue University

b. Explain why the ball speeds up as it falls, using your knowledge of impulse and momentum.

c. Explain why the ball speeds up as it falls, using your knowledge of Newton’s laws.

c. Discuss the differences in the bar charts because of the choice of system. f. Discuss whether the explanations based on impulse-momentum and Newton’s laws are consistent with each other.

Acti Activity vity 4: Elizabeth pushes cart A, which is initially at rest, along a horizontal track toward cart B, which is also initially at rest. Before Elizabeth started pushing the cart, Daniel had started recording the motion of cart A using a motion detector. He obtained the following velocity-versus-time graph for cart A:

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Sama Pouri

PHYS 2 220 2000, Purdue University

a. Estimate the clock reading when the carts collided.

b. Based on the data from the graph, can you estimate the ratio of the average force exerted by Elizabeth on cart A and the force exerted by cart A on cart B during the collision? If you think you can, determine this ratio. If you think you cannot do so, what additional data would you need to be able to determine this ratio?

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