# Impulse Q

#### glasgowm

A cue exerts an average force of 7N on a stationary snooker ball of mass 200g if the impact lasts for 45ms, with what speed does the ball leave the que?

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Ft = mv - mu
F = m(v-u/t)
F = 0.2(v-0/0.0045)
= 0.2v/0.0045 = 44.4444V

Can't figure out what the next step is from my notes.

Cheers

#### radou

Homework Helper
glasgowm said:
A cue exerts an average force of 7N on a stationary snooker ball of mass 200g if the impact lasts for 45ms, with what speed does the ball leave the que?

---

Ft = mv - mu
F = m(v-u/t)
F = 0.2(v-0/0.0045)
= 0.2v/0.0045 = 44.4444V

Can't figure out what the next step is from my notes.

Cheers
Simply stated, the impulse equals the change of linear momentum, so, you have: $$F\cdot t = mv_{2}-mv_{1}$$, where m is the mass of the ball, v2 the final velocity and v1 the initial velocity (equals zero). From this equation you can easily retrieve v2.

#### glasgowm

radou said:
Simply stated, the impulse equals the change of linear momentum, so, you have: $$F\cdot t = mv_{2}-mv_{1}$$, where m is the mass of the ball, v2 the final velocity and v1 the initial velocity (equals zero). From this equation you can easily retrieve v2.
I already did that.

#### radou

Homework Helper
glasgowm said:
I already did that.
I saw you did that and I don't see where the problem is. Just plug in the force and solve to get the speed v.

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