# Homework Help: Power and force

1. Mar 19, 2015

### goonking

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

During a tennis serve, the ball goes from rest to approximately 32.3 m/s. The average power generated during the serve is equal to 2672 Watts. If the acceleration is constant during the serve, what is the magnitude of the force acting on the ball?
2. Relevant equations

P= F v
3. The attempt at a solution
they give us the power generated which is 2672 Watts and final velocity to be 32.3 m/s. Do we just divide 2672 watts by 32.3 m/s?

2. Mar 19, 2015

### PhanthomJay

No, the power given is average power, not instantaneous power.

3. Mar 19, 2015

### goonking

i'm assuming we have to find the total time for this problem, correct?

4. Mar 20, 2015

### PhanthomJay

No, you were on track with your solution using the relationship between power , force, and speed per your relevant equation. Except you used the final speed for v in error. Instead, what value should you use for v when you are dealing with average values?

5. Mar 20, 2015

### goonking

ahh, the average velocity which is 32.3 - 0 / 2 = 16.15 m/s

6. Mar 20, 2015

### PhanthomJay

Yes

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted