Momentum Inertia in Motion What is momentum Momentum

Momentum Inertia in Motion

What is momentum? • Momentum is a commonly used term in sports. A team that has the momentum is on the move and is going to take some effort to stop. • A team that has a lot of momentum is really on the move and is going to be hard to stop. • The sports announcer says "Going into the all-star break, the Chicago Cubs have the momentum. " • Coach Havlik pumps up his team at half -time, saying "You have the momentum; the critical need is that you use that momentum and bury them in this third quarter. "

What is momentum? • Momentum is a physics term; it refers to the quantity of motion that an object has. A sports team which is on the move has the momentum. If an object is in motion (on the move) then it has momentum. • “The quantity of motion … arising from velocity and the quantity of matter conjointly. ” • Isaac Newton • Any object which has both mass and a velocity is said to have momentum. • “Inertia in motion”

Components of Momentum • Momentum = mass × velocity p = m x v • Units: kg m/s Therefore, massive objects moving at a high speed have a large momentum

Two cases of Momentum • A slow moving elephant has a large momentum. • Even though it has a small velocity, it has a lot of mass • A bullet has a large momentum • Even though it has a small mass, it has a very large velocity

Comparing Momentum Which would have a larger momentum: - A 10 mph bowling ball or a 10 mph pingpong ball? Which is harder to stop? - Two cars of the same mass, one moving at 60 mph and the other moving at 30 mph?

Conservation of Momentum • “The total momentum of any given system will remain constant unless acted upon by an external force. ” or • The momentum before a collision is equal to the momentum after a collision.

Example • When a bullet is fired from a gun, what happens?

Example • The bullet moves in the forward direction and the gun kicks backward. Before firing, the total momentum of the system was zero. When the bullet is fired it gains some momentum (due to velocity acquired by it). In response, the gun moves in the opposite direction such that its momentum is equal in magnitude but opposite in direction to the momentum of the bullet.

Momentum Transfer • Remember: Momentum is transferred not lost • Conservation of Momentum Video