Impulse Physics Example 4

Follow the full solution, then compare it with the other examples linked below.

Example 4

medium
A 0.20 kg0.20 \text{ kg} hockey puck moves at 3 m/s3 \text{ m/s} east, then is struck and moves at 7 m/s7 \text{ m/s} west. What impulse was delivered to the puck?

Solution

  1. 1
    Take east as positive, so vi=+3 m/sv_i = +3 \text{ m/s} and vf=−7 m/sv_f = -7 \text{ m/s}.
  2. 2
    Impulse equals change in momentum: J=Δp=m(vf−vi)J = \Delta p = m(v_f - v_i)
  3. 3
    J=0.20(−7−3)=0.20(−10)=−2.0 kg m/sJ = 0.20(-7 - 3) = 0.20(-10) = -2.0 \text{ kg m/s}

Answer

J=−2.0 N sJ = -2.0 \text{ N s} (that is, 2.0 N s2.0 \text{ N s} west)
Impulse is a vector equal to the change in momentum. Reversing direction creates a larger momentum change than simply slowing down.

About Impulse

The product of force and time interval, equal to the resulting change in an object's momentum.

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More Impulse Examples

Example 1 easy

A force of [formula] acts on a ball for [formula]. What is the impulse delivered to the ball?

Example 2 medium

A [formula] baseball moving at [formula] is hit by a bat and reverses direction at [formula]. What i

Example 3 medium

A [formula] person jumps and lands on the ground, changing velocity from [formula] (downward) to [fo

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