# Homework Help: Nonconservative work while swimming

1. Nov 4, 2008

### flemj

1. The problem statement, all variables and given/known data

Starting at rest at the edge of a swimming pool, a 67.0 athlete swims along the surface of the water and reaches a speed of 1.15 by doing the work = 171 . Find the nonconservative work, , done by the water on the athlete.

2. Relevant equations

(m)(a)(x initial) + .5 (m)(v^2 initial) = (m)(a)(x final) + .5 (m)(v^2 final)
E=UK
W=Fd
F=ma
K=.5 mv^2
3. The attempt at a solution

Im not really sure how to tackle this problem those are the equations i think i need to use but should it go something like

K=.5(67kg)(1.15m/s^2) so K=44.3
E=UK (U being the work?) E= (171)(44.3) E=7575.3

i dont know what im doin i need some help that'd be great

Last edited: Nov 4, 2008
2. Nov 4, 2008

3. Nov 4, 2008

### flemj

sorry i wrote that down wrong but your saying i want to use W=Delta Ek ? how do i go about that tho? by using K=.5 mv^2?

4. Nov 4, 2008

### physics girl phd

Think again about the physics... NOT just equations!
You're swimming. You use some chemical energy to do that: how much?

Then: what do you get out of it?

Then: As the problem asks for: Did you get everything out of it that you could have if the situation worked perfect for you? If not: what did you lose in the process?

5. Nov 4, 2008

### flemj

yes so while swimming my conservative energy would be 77.05 and in a nonconservative force im losing some of that energy due to the friction and the heat that im giving off etc. to solve for this equation do i need to find the distance i have swam ? i understand why it happend just now how to calculate the lose