# Work Theory Question

1. Dec 6, 2004

### DLxX

Could you help me out with this question?

A woman swimming upstream is not moving with respect to the shore. Is she doing any work? If she stops swimming and merely floats, is work done on her?

2. Dec 6, 2004

### Sirus

$$W=Fd\cos{\theta}$$

Distance can be defined relatively. Therefore, she is not doing any work with respect to the shore, but she is doing work with respect to the water (she travels a distance with respect to the water). Use this idea to answer the second question. What happens if she stops swimming?

3. Dec 7, 2004

### Clausius2

I don't really know what means to do work respect to something. The work is done, and is some amount of energy, respect to nothing. In both cases there is work done:

-In the first one, although the woman remains stationary respect to the shore, she is moving her arms, so that is doing a work over the water (that work is eventually transformed into internal energy and lately dissipated).

-In the second one, there is work done over the woman by the water, because there is a transferring of mechanical energy between the waves (I suppose there are waves in the sea ) and the woman.