# Quick homework question

1. Apr 2, 2009

### nelly42688

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

A 100kg block is pulled at a constant speed of 5.0 m/s across a horizontal floor by an applied force off 122N directed 37 degrees above the horizontal. What is the rate at which the force does work on the block?

2. Relevant equations

I know here we will use the instantaneous power formula P=dW/dt or P=Fvcos

3. The attempt at a solution

well i drew the FBD and started plugging in numbers in my formula, its just im not sure where the Mass falls into place here I know the answer is 4.9x10$$^{}2$$ watts but not sure where to go from here thanks

2. Apr 2, 2009

### rl.bhat

In this problem mass is not needed.

3. Apr 2, 2009

### nelly42688

well my answer just doesnt match up with the answer my teacher gave us and i dont know why.... i did 122*5.7sin(37) and came up with 418.5W or 4.2X10^2 W

4. Apr 2, 2009

### rl.bhat

Your calculation is wrong.
122*5*cos(37) = ?

5. Apr 2, 2009

### nelly42688

wow! the whole time i was using 5.7m/s instead of 5m/s careless mistake sorry to waste your time

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