Motion of a jumper - Find the mass

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Homework Help Overview

The problem involves a high jumper who falls and comes to rest after landing on a foam pit, with specific parameters given such as the jumper's initial speed, the distance the pit compresses, and the average force exerted by the pit. The subject area relates to dynamics and forces in motion.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the average acceleration of the jumper during the interaction with the foam pit and how to apply the equations of motion to find the mass. There are attempts to relate the force exerted to the mass using F = ma, while also considering the jumper's weight.

Discussion Status

The discussion is ongoing, with hints provided regarding the calculation of acceleration and the application of forces. Participants are exploring different interpretations of the problem and how to approach the calculations without reaching a consensus yet.

Contextual Notes

There is an emphasis on not neglecting the weight of the jumper when applying the net force in the calculations. The problem setup includes specific values that are critical for solving the mass but does not provide all necessary information directly.

Jess048
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A high jumper falling at 3.9 m/s, lands on a foam pit and comes to rest, compressing the pit a distance of 0.43 m. If the pit is able to exert an average force of -1100 N on the high jumper in breaking the fall, what is the jumper's mass?

I don't know where to begin so anything can help!:confused:
 
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Hint: What was the average acceleration of the jumper during his interaction with the foam?
 
Remember that with acceleration -a and initial speed v0, the speed at time t is v(t)= -at+ v0 and the distance moved is x(t)= -(a/2)t2+ v0t. To come to a halt, v(t)= 0= -at+ v0 so requires t= v0/a second. In that time, according to the problem, the jumper moved -(a/2)t2+ v0= 0.43 m. Plug the value of t (as a function of a- you are given v0) into that and solve for a. The solve ma= F(which is given) for m.
 
In applying F = ma, be sure to use the net force on the jumper. (Don't neglect his weight.)
 

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