• Define linear momentum and impulse and describe the relationship between the two.
• Describe situations under which linear momentum is conserved and be able to solve for the velocities of objects in such situations.
• Differentiate between elastic and inelastic collisions.  Describe what quantities are conserved in both situations and be able to solve for the velocities of objects involved in such collisions.

1. If a particle's kinetic energy is zero, what is its momentum? If a particle's total energy is zero, is its momentum necessarily zero? Explain.
2. If two objects collide, and one is at rest, is it possible for both to be at rest after the collision?
3. How do car bumpers work to protect you in a car accident?
4. If two particles have equal kinetic energy, do they have the same momentum?

Problems

1. A pitcher claims he can throw a .145 kg baseball with as much momentum as a 3.00 gm bullet moving with a speed of 1.50 x 10³ m/s. (a) What must the baseball's speed be if the pitcher's claim is valid? (b) Which has greater kinetic energy, the ball or the bullet?
2. High-speed stroboscopic photographs show that the head of a 200 gm golf club is traveling at 55 m/s just before it strikes a 46 gm golf ball at rest on a tee. After the collision, the club head travels (in the same direction) at 40 m/s. Find the speed of the golf ball just after impact.
3. A 10.0 gm object moving to the right at 20.0 cm/s makes an elastic head-on collision with a 15.0 gm object moving in the opposite direction at 30.0 cm/s. Find the velocity of each object after the collision.

Solutions

Last Modified: September 28, 2006