** Forces
Transfer Momentum** (2.4)

· The “Big Idea”:

- Forces change the motion of objects in
predictable ways.

· Now you will learn:

- What ** momentum** is

- How to calculate momentum

- How momentum is affected by collisions

**Objects
in motion have momentum.**

· ** Momentum- ** a measure of mass in motion; the
momentum of an object is the product of its

- At the same velocity, a bowling ball has
more momentum than a tennis ball because it has more mass.

- How could you increase the momentum of
the tennis ball?

You
could increase the momentum by throwing it faster.

· How is momentum
similar to inertia? How is it different?

Momentum
is similar to inertia since it depends on mass. It is different because it takes into account how fast an
object is moving.

· Would a slower
moving wrecking ball do as much damage as a faster moving one?

No. The faster an
object is moving the more damage it would do.

· Calculating momentum:

**momentum= mass x velocity**

*p= mv*

· Units: kg m/s

__Practice:__

1. What is the
momentum of a 2 kg ball moving at 2 m/s?

*p= mv
*

*p= 2 kg x 2 m/s*

*p= 4 kg m/s*

2. What is the momentum of a 4 kg rock
moving at 3 m/s?

*p= mv
*

*p= 4 kg x 3 m/s*

*p= 12 kg m/s*

**Momentum
can be transferred from one object to another.**

· ** Collision-** A situation in which two objects in
close contact exchange energy and momentum.

- In a collision,
action/reaction forces transfer momentum.

- Think of bumper
cars:

**1.
**As another car bumps the back of yours, the force
pushes your car forward.

**2.
**Momentum is transferred from that car to your car.

**3.
**The car behind you slows because of the reaction
force of your car.

**4.
**You gain momentum from the collision.

*** If colliding objects have very different masses, then
the one with less mass has a greater change in velocity. *

**Momentum is conserved.**

·
** Conservation of momentum**- The total momentum of a system of
objects does not change, as long as no outside forces are acting on them.