Find MASS of a runner when work, power, and velocity are given?

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Homework Help Overview

The problem involves calculating the mass of a runner based on given values of power, velocity, and energy dissipation per step. The context is related to mechanics and energy transfer during running.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • Participants discuss the relationship between power, work, and time, suggesting that the work done per step could be analyzed. There is uncertainty about the appropriate equations to use for finding mass.

Discussion Status

Some participants have offered insights into how to relate power to work done over time, while others express confusion about the equations needed to isolate mass. Multiple interpretations of the problem are being explored, but no consensus has been reached.

Contextual Notes

Participants are working with the assumption that the energy dissipation is consistent per step and are considering the implications of this on the calculations. There is a noted lack of clarity regarding the equations necessary to proceed.

kalisious
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Homework Statement


While running in a cross country meet, a member of the team dissipates about 0.35J of mechanical energy per step per kg of her body mass. If she develops a power of 75W during the race and runs at a speed of 5m/s, find her mass.
PS: Consider one [of her] running steps to be 1m.


Homework Equations


I am unsure what equation to use to find mass. I know the equations to find power and work, but in relation to finding mass I am unsure.


The Attempt at a Solution


I cannot attempt a solution with no clue what equation to use to get me started.
I am able to do the work if I have proper equations.
Thanks!
 
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Looks like the 75 Watts goes into making those steps.
P = W/t so you need to figure out the work done stepping over some convenient time. Maybe you could do it for one step?
 
I am not sure what equation is used to find the mass though?
 
It says the energy used is 0.35 J per kg. So the energy used is 0.35*m.
If you put that in the equation, you'll be able to solve for m.
 

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