Collisions: Ball with initial velocity is kicked, force of kick?

  • Thread starter Merlinnair
  • Start date
  • #1

Homework Statement


A 10 g ball going at a speed of 5 m/s is kicked, and flies off at an angle of 35° at 25 m/s. What was the force of kick?
Known:
m = 0.0010 kg
vi = 5 m/s
θ = 35°
vf = 25 m/s

Homework Equations


mvi = mvf
F = ma

The Attempt at a Solution


Would this count as an inelastic collision?
In the x direction:
.0010g(5m/s) + m(0m/s) = (.0010 kg + m)(25cos35)

After that, I'm really not sure how to get to the acceleration...
 

Answers and Replies

  • #2
Doc Al
Mentor
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This is an impulse-momentum problem, not a momentum conservation problem. (You'll need the time during which the kick was applied.)
 
  • #3
In that case, I might have forgotten a variable, as I don't have the question with me. So if I had the time...

Impulse is F/t and change in momentum right?

So then, all I'd have to do is set F/t = p_i - p_f?
 
  • #4
Doc Al
Mentor
45,033
1,336
Impulse is F/t and change in momentum right?
Almost. Impulse is F*t, not F/t.
So then, all I'd have to do is set F/t = p_i - p_f?
Set impulse = Δp. (FYI: Change in something is always final - initial.)
 
  • #5
Oh, right, typo on the change in part, and I really do need to start memorizing my equations. Thanks for your help!
 

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