MomentumMomentum&&

Impulse Impulse

What does it mean to say “roll with the punches?”

Why is it important to wear a helmet?

Is it a good thing that cars basically crumble in an accident?

Momentum

What is momentum?

Can these two things have the same momentum?

Which of these will have the greater inertia? How do you know?

How can

have the same momentum as

?

The little girl can have the same momentum as the elephant if, when they are moving, her velocity is much greater than that of the elephant.

Momentum is:Inertia in motion… or mass in motion

Momentum (p) is the mass of an object multiplied by its velocity:

p = mvUnits:Momentum is measured in kgm/s

Impulse

What is impulse?

The Egg Test!

Impulse:

Impulse is a change in momentum. It occurs when a force is exerted on an object over a certain amount of time:

Impulse (J) = force times timeJ = F x t

Can we prove that:

Ft = ∆mv

The rubber ball paradox

Elastic and Inelastic

What does it mean to be Elastic?

What does it mean to be Inelastic

Elastic vs Inelastic Collisions

Elastic Collision: When an object collides with another object and returns back to its original form.

-a collision when a object bounces off another object (they don’t stick together)

Inelastic Collision: When an object collides with another object and does not return to its original form.

-when two objects stick together (don’t bounce off each other)

Conservation of Momentum

What does it mean to say the word:

CONSERVE

Conservation of Momentum

All momentum is conserved before an event and after an event.

In other words. No momentum is ever lost. What we start with is what we end with. The TOTAL momentum never changes.

Conservation of Momentum Problem:

A 7000kg truck moving with a velocity of 8m/s runs into and sticks to the back of a parked car that has a mass of 2000kg. What is the velocity of the combined cars after they collide?

#2

An Ice Hockey puck with mass 2kg is moving with a velocity of 3m/s. It then collides with a stationary rok that has a mass of .5 kg. If the rok bounces off the puck with a velocity of 4m/s, how fast is the puck moving?