- #1

KevinFan

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## Homework Statement

After winning a prize on a game show, a 72 kg contestant jumps for joy.

A.

If the jump results in an upward speed of 2.1 m/s, what is the impulse experienced by the contestant?

b. 0.0

c. 75.6 kg.m/s

d. 151.2 kg.m/s

e. 226.8 kg.m/s

B.

Before the jump, the floor exerts an upward force of magnitude mg on the

contestant. What additional average upward force does the floor exert if the contestant pushes down on the floor

for 0.36 s during the jump?

a. 0.0

b. 210.0 N

c. 420.0 N

d. 630.0 N

## Homework Equations

P=mv

delta p= f*delta t

## The Attempt at a Solution

For part A: Since the contestant is on the ground initially, he has zero momentum, and after he jump his final speed is 2.1m/s. P=mv, I calculated 151.2 kg*/s as his change in momentum. However, the answer for this part should be 75.6kg*m/s...

For part B I used the impulse divide by time to get the average force, and the value is 420N. The answer is 420 N but I thought that I should use mg substruct 420N to get the "additional force"

Any suggestions please?