Collisions

Momentum Conservation and Collisions

Conservation

• Requires zero total external force

• Internal forces act within a system and do not change the total momentum

• External forces act on a system and change the total momentum

• Individual momentum's can vary as long as the total remains constant.

Open Ended

Two groups of people are in canoes motionless on a lake. One person pushes the opposite canoe away. Is there an external force acting on the system? Why or why not?

Multiple Choice

Two groups of people are in canoes motionless on a lake. One person pushes the opposite canoe away with a force of 46 N. The force lasts for 1.2 sec and moces the canoes in opposite directions. What is the momentum of each canoe after the push?

• 46

• 55.2

• 38.3

• .026

Multiple Choice

What is the final velocity of each canoe if canoe 1 is 130 kg and canoe 2 is 250 kg.

• -.56, .34

• -2.3, 4.5

• -.42,.22

• -.27, .14

Recoil

Each table needs to provide an example of Recoil at work in a real world environment

Inelastic collisions

• Kinetic energy changes

• Energy transforms into other forms. Give examples of energy forms

• Completely inelastic collisions. Stay together