Lesson 3: Momentum and Velocity
Understanding Momentum and Velocity
Momentum is the product of an object's mass and velocity. It is a vector quantity represented by the symbol p and calculated as p = mv.
Momentum is basically mass in motion. Have you ever heard the story of how a coconut falling is more deadly than a bullet? This is because a coconut is heavier even though a gun is faster. A coconut has more momentum than a bullet, and that's how we know that it's more deadly.
Example Problems
Example problem:
How much momentum does a 15 kg block traveling at a velocity of 7 m/s north have?
Solution:
Momentum = Mass * Velocity
= 15 kg * 7 m/s
= 105 kg*m/s north
Another example:
A 10 kg ball moving at a speed of 6 m/s strikes another 5 kg ball at rest with a contact time of 0.5 seconds. The 10 kg ball comes to a complete stop. What average force was exerted on the 10 kg ball?
Solution:
Change in momentum = Final momentum - Initial momentum
= 0 - (10 kg * 6 m/s)
= -60 kg*m/s
Force = Change in momentum / Time
= -60 kg*m/s / 0.5 s
= -120 N