1. Physics Section 6.3 Apply the physics of collisions Inelastic collision – two objects stick together after colliding. The two objects become one object. In a perfectly inelastic collision, the momentum is conserved and kinetic energy is lost. m 1 v 1i + m 2 v 2i = (m 1 + m 2 )v f m = mass (kg) v = velocity (m/s)

2. problem A stationary boxcar with a mass of 25,000 kg is struck by another boxcar with a mass of 45,000 kg at a velocity of 2.5 m/s. If the cars become attached, what is their resulting velocity?

3. problem A cart with a mass of 150 kg is traveling north with a velocity of 3.2 m/s. It collides in an inelastic collision with a cart with a mass of 120 kg, and a velocity of 2.4 m/s south. Find the resulting velocity after the collision.

4. Kinetic Energy is NOT conserved in an inelastic collision. A clay ball with a mass of.35 kg hits another.25 kg clay ball and sticks together. The 1 st ball had a velocity of 1.5 m/s east and the 2 nd ball had a velocity of 2.2 m/s west. Find the change in kinetic energy before and after the collision.

5. Elastic collision – two objects collide and rebound. In a perfectly elastic collision, total momentum is conserved, and total kinetic energy is conserved. The momentum of the objects is exchanged during the collision. http://www.teachertube.com/viewVideo.php?video_id=15865&title=Momentum_and_C ollisions m 1 v 1i + m 2 v 2i = m 1 v 1f + m 2 v 2f (Momentum) ½ m 1 (v 1i ) 2 + ½ m 2 (v 2i ) 2 = ½ m 1 (v 1f ) 2 + ½ m 2 (v 2f ) 2 (energy) m = mass (kg) v = velocity (m/s)

6. problem A marble with a mass of.015 kg is moving right with a velocity of.225 m/s. It collides with a.030 kg marble with a velocity of.180 m/s left in an elastic collision. After the collision, the smaller marble moves to the left with a velocity of.315 m/s. a. Find the velocity of the 2 nd marble after the collision. b. Find the total kinetic energy before and after the collision.

7. assignment Page 220 Problems 1-5