Momentum Physics Example 4

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

Example 4

medium
A 1200 kg1200 \text{ kg} car moves east at 25 m/s25 \text{ m/s} while a 1000 kg1000 \text{ kg} car moves west at 10 m/s10 \text{ m/s}. What is the total momentum of the two-car system?

Solution

  1. 1
    Take east as positive.
  2. 2
    Momentum of the first car: p1=mv=1200×25=30000 kg m/sp_1 = mv = 1200 \times 25 = 30000 \text{ kg m/s}
  3. 3
    Momentum of the second car: p2=1000×(−10)=−10000 kg m/sp_2 = 1000 \times (-10) = -10000 \text{ kg m/s}
  4. 4
    Total momentum: ptotal=30000+(−10000)=20000 kg m/sp_{\text{total}} = 30000 + (-10000) = 20000 \text{ kg m/s}

Answer

ptotal=2.0×104 kg m/s eastp_{\text{total}} = 2.0 \times 10^4 \text{ kg m/s east}
Momentum is a vector quantity, so direction matters. Opposite directions produce opposite signs and partial cancellation when the momenta are added.

About Momentum

The product of an object's mass and velocity, representing the quantity of motion it carries.

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More Momentum Examples

Example 1 easy

A [formula] ball moves at [formula]. What is its momentum?

Example 2 medium

A [formula] car moving at [formula] and a [formula] bullet moving at [formula]. Which has greater mo

Example 3 easy

What velocity must a [formula] ball have to possess a momentum of [formula]?

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