MYIB / Honors Physics

Impulse and Momentum

Using Physics terms, what put the egg in motion?

Once the egg was moving, why did it keep moving?

Momentum equals mass times velocity.

Unit:

Using Physics terms, how did you stop the egg?

Then if you multiply both sides by “t”, then

Notice the right side of the equation,What physics term is defined by that part of the equation?

The quantity Ft is called an Impulse.

Impulse = Change in Momentum

Units of Impulse: Units of Momentum:

Example1. A 5.00 kg mass initially at rest is acted on by a horizontal force of 20.0 N for

a time of 3.50 s.a. What is the change in momentum of the mass?      a. What is the speed of the mass at the end of the 3.50 s?      

ExampleA 4.00 kg object moving at 5.00 m/s is acted on by an unknown force for 10 s until it reaches a speed of 15.0 m/s.a.What is the initial momentum of the object?b. What is the final momentum of the object?c. What is the change in momentum of the object?d. What is the magnitude of the force that acted on the object?    

Impulse is the AreaSince J=Ft, Impulse is the AREA of a Force vs.

Time graph.

If the tennis ball is released at eye level and allowed to fall freely due to the pull of gravity, is it possible for the tennis ball bounce higher than your head without placing anything on the ground for the ball to bounce off?

Momentum is conserved in the collision!The Law of Conservation of Momentum:

Several Types of collisionsSometimes objects stick together or blow apart.

In this case, momentum is ALWAYS conserved.

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Example Granny (m=80 kg) whizzes around the rink with a velocity of 6 m/s. She suddenly collides with Ambrose (m=40 kg) who is at rest directly in her path. Rather than knock him over, she picks him up and continues in motion without "braking." Determine the velocity of Granny and Ambrose.

ExampleAt an amusement park, a 96.0 kg bumper car (A) moving right with a speed of 1.50 m/s bounces elastically off a 135 kg bumper car (B) at rest. After the collision, bumper car B moves right with a speed of 0.8888 m/s. What is the speed and direction of bumper car A after the collision?