**Momentum Conserved **

Savannah Walker Mason School

4712 Keeler Street

Chicago IL 60623

(312) 534-1530

**Objectives**:
The students will apply two of Newton's Laws of Motion discovering that
Momentum is conserved.
**Materials**:
Newton's Cradle
Carts
Planks with skates screwed to the bottom
"Crash Dummy Motorcycle"
**Strategy**:
NEWTON'S CRADLE--Collision
Pull one ball out. Ask "What will happen when I let go?" Let everyone
contribute. Then let go. See what actually happens. Do not get into a big
discussion at this point! Come back to this at the end.
TWO CART COLLISION--
Define Momentum: Mass x Velocity. Have two carts of equal mass collide with
each other from opposite directions. Ask "What happened?" Let everyone
contribute. (Newton III, and Momentum is Conserved)
Then have the two carts collide when one of the carts is the same mass as
previously and the other has a third cart stacked on top-a larger mass. Ask
"What happens?" Let everyone contribute. (still Newton III, also Newton II,
Momentum is Conserved)
PLANK WITH ROLLER SKATES ATTACHED--
Have a student walk the plank. Ask "What happened?" (Plank goes the other
way.) Let every student contribute. Have students of different weights take
turns. Observe any difference this makes. (Newton III, Momentum is Conserved)
CRASH DUMMY MOTORCYCLE--
Construct a "Wall" at the end of an inclined plane. Have the motorcycle with
the dummy rider crash into the wall. Ask "What happened?" (Newton III, also
Newton I, Momentum is Conserved)
NEWTON'S CRADLE REVISITED--
Go back to the Newton's Cradle. Again pull out one ball. Let go. Ask "What
happened?" and "Why?" Students should be able to discuss the results in terms
of Newton's Laws for each ball's collision with the next ball. They should also
recognize that Momentum is Conserved in each collision. Now try this with two,
three, or even four balls. They should be able to extend their conclusions to
these unequal mass collisions.

Return to Physics Index