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A 125 g snowball is traveling with a speed of 22 m/s when it hits the fence. If the snowball is completely stopped by the fence and does not rebound, what is the impulse of the force of the fence on the snowball?

1 Answer

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Answer: 2.75 kg*m/s

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Step-by-step explanation:

I'll use these variables

  • F = force
  • m = mass
  • a = acceleration
  • v = velocity
  • t = time
  • i = impulse

though as shown below, we have the time variable cancel out

F = ma .... newton's second law

F = m*(v/t)

i = F*t

i = m*(v/t)*t

i = m*v

The impulse is the product of mass and velocity

In this case, we have

  • m = 125 grams = 0.125 kg
  • v = 22 m/s

So,

i = m*v

i = (0.125 kg)*(22 m/s)

i = (0.125*22) kg*m/s

i = 2.75 kg*m/s

This is equivalent to 2.75 Ns where "Ns" is an abbreviation of "Newton seconds". It's effectively multiplying the Newton unit with the seconds unit.

The impulse is the change in momentum. So the snowball has a change of momentum of 2.75 kg*m/s

User Laurent K
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