# Chapter 7 Impulse and Momentum (PowerPoint) by dfhdhdhdhjr

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```									      Chapter 7
Impulse and Momentum
Chapter 7
Impulse and Momentum
Concepts learned so far:
•Impulse
•Momentum
•Impulse-Momentum theorem
•Conservation of momentum
Collisions in Two
Dimensions
Collisions in Two
Dimensions
Collisions in Two
Dimensions

1. Apply conservation of momentum in the X direction.
Collisions in Two
Dimensions

1. Apply conservation of momentum in the X direction.
2. Apply the conservation of momentum in the Y direction.
Collisions in Two
Dimensions

1. Apply conservation of momentum in the X direction.
2. Apply the conservation of momentum in the Y direction.
3. If the collision is elastic, apply the conservation of energy.
Problem 35
A 50.0-kg skater is traveling due east at a speed of 3.00 m/s. A
70.0-kg skater is moving due south at a speed of 7.00 m/s. They
collide and hold on to each other after the collision, managing to
move off at an angle θ south of east, with a speed of vf. Find (a)
the angle θ and (b) the speed vf, assuming that friction can be
ignored.
7.5 Center of Mass
The concept center of mass (abbreviated as “cm”) is
very useful in dealing with larger objects.
For example, in dealing with Earth, we placed the
mass of Earth at the cm of the Earth.

Earth
Definition of CM

The center of mass is a point that represents the average
location for the total mass of a system.
Center of Mass
Where is the cm of the following two 5-kg masses?
Center of Mass
Where is the cm of the following two 5-kg masses?

Center of Mass
Where is the cm of the following two, 5-kg & 12-kg
masses?
Center of Mass
Where is the cm of the following two, 5-kg & 12-kg
masses?

Answer: The center of mass “cm” of the two masses is
located on a line between them and lies closer to the more
massive 12-kg mass.
Center of Mass
CM of point masses
Velocity of the CM of point
masses

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