# Physics 11, kinetic energy problem

Hey if anyone could help me work through a couple of problems that would be great! ## Homework Statement

It is not uncommon during the service of a professional tennis player for the racquet to exert an everage force of 150.0N on the ball. If the ball has a mass of 0.060kg and is in contact with the strings of the racquet for 0.030s what is the kinetic energy of the ball as it leaves the racquet? Assume the ball starts from rest

Ek=1/2mv^2

## The Attempt at a Solution

I'm not sure really where to start here....

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Homework Helper
A hint: impulse.

Well, you know what you'll need to find Kinetic Energy--mass and velocity. You're given mass. Can you think of any other equations that might help you find velocity?

what do i do once i've figured that out?

d=vt but i don't have a distance either

Once you've figured what out?

oh my god i think i got it, will someone let me know if i got it right, just let me work it out.

Homework Helper
There is no need to create so many posts. i got 169J

Looks OK to me, whose brain is fried!

Last edited:
cristo
Staff Emeritus
i got 169J
That's correct.

p=Ft
p=150(0.030)
p=4.5

p=mv
4.5=(0.06)(v)
v=75m/s

Ek=1/2m^2
Ek=1/2(0.060)(75^2)
Ek=169J

Ok i have a couple of other question so if anyone wants to stick around and help...?