Problem 1

What is the momentum of a 23 kg rock rolling at 17 m/s?

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Need a hint?

Given: m = 23 kg   v = 17 m/s

Want to find p = ?

Equation p = mv

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Check Your Answer

p = mv

p = (23) (17)

p = 391 kg m/s

Problem 2

A 72 kg person is running with a momentum of 432 kg m/s. What is his velocity?

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Need a hint?

Given: m = 72 kg   p = 432 kg m/s

Want to find v = ?

Equation: p = mv

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Check Your Answer

p = mv

v = p/m

v = 432/72

v = 6 m/s

Problem 3

As a part of a lab you are doing in school, you roll five marbles made of different materials down a ramp. At the bottom of the ramp you have a photogate that can precisely measure the velocity. Record the data in the chart below.

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Note

If this has been objects sliding down a frictionless ramp, the velocities at the bottom would be the same. Since these objects are rolling and made of different material, frictional and rotational effects cause differences in the velocities. I have made these differences bigger than they would likely be in a real lab to better show the steps of the calculation.

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Need a hint?

Calculate p = mv for each of the marbles, then add the answers together.

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Check Your Answer

Mass (kg)	Velocity (m/s)	Momentum (kg m/s)
m	v	p = mv
0.2	3.2	0.64
0.5	2.1	1.05
0.3	2.2	0.66
0.25	4.8	1.20
1.0	1.7	1.70
		Total = 5.25 kg m/s