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

[kalisious]

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!

 

[Delphi51]

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?

 

[kalisious]

I am not sure what equation is used to find the mass though?

 

[Delphi51]

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.