4.27. Momentum http://www.ck12.org
A: Jerod obviously has greater mass than Cody, so he would have greater momentum. He would also be harder to
stop.
FIGURE 4.51
You can see an animation demonstrating the role of mass and velocity in the momentum of moving objects at this
URL:
http://www.science-animations.com/support-files/momentum.swf
Calculating Momentum
To calculate momentum with the equation above, mass is measured in (kg), and velocity is measured in meters per
second (m/s). For example, Cody and his skateboard have a combined mass of 40 kg. If Cody is traveling at a
velocity of 1.1 m/s by the time he reaches the bottom of the ramp, then his momentum is:
Momentum = 40 kg×1.1 m/s = 44 kg • m/s
Note that the SI unit for momentum is kg • m/s.
Q: The combined mass of Jerod and his skateboard is 68 kg. If Jerod goes down the ramp at the same velocity as
Cody, what is his momentum at the bottom of the ramp?
A: His momentum is:
Momentum = 68 kg×1.1 m/s = 75 kg • m/s
Summary
- Momentum is a property of a moving object that makes it hard to stop. It equals the object’s mass times its
velocity. - To calculate the momentum of a moving object, multiply its mass in kilograms (kg) by its velocity in meters
per second (m/s). The SI unit of momentum is kg • m/s.
Vocabulary
- momentum: Property of a moving object that makes it hard to stop; equal to the object’s mass times its
velocity.