Physics question

Question

Physics question

greatlife44 · Answer

If Alice does 10 Joules of work while pushing Jeff in 5 seconds, and the force of friction due to the broken toboggan did 2 joules of work, how much work did Alice exert?

greatlife44 · Answer

it should be how much power did alice exert?

greatlife44 · Answer

here are the choices 

50 W
2 W
1.6 W
1.5 W

greatlife44 · Answer

$$W - W_{friction} = net~work $$

$$10-2 = 8 J $$

then I knew power was Joules/time 

$$\frac{ 8J }{ 5s } = 1.6 W $$

greatlife44 · Answer

BTW my answer is wrong

data_lg2 · Answer

Power is the rate of doing work. (P= W/t)

$Work = F_{applied}• displacement. $ 

Work applied by Alice is different from the work applied by the friction. In this problem you are only concerned about Alice's work.

greatlife44 · Answer

okay so power only applies to the work done by a particular source right?

data_lg2 · Answer

yeah