1. CMHS Physics
Momentum
Mr. Pacton

2. Review Problem 1
A 150 g baseball moving at a speed of 45.0 m/s crosses the plate and strikes the kg catcher's mitt (originally at rest). The catcher's mitt immediately recoils backwards and moves together with the ball. If the catchers hand is relaxed, and it is assumed that no net external force exists, then the law of momentum conservation applies to the catcher's mitt and ball. Determine the post-collision velocity of the mitt and ball together. What work must be done by the Catcher to bring the Ball and Mitt to rest?

3. Solution m1vi1 + m2vi2 = (m1 + m2)VF
Initial Total Momentum = Final Total Momentum
.15 x = ( ) VF
VF = (.15 x 45) / ( ) = m/s
W= DKE = 0 – ½ (m1 + m2)VF2 = .5(.4)(16.875)2
= 57 J

4. Momentum Conservation Example
Determine the forward momentum and velocity of the rocket shown. Initially it is at rest, but later it has a mass of 1050 kg as it extrudes 250 kg of gas at a velocity of 350 m/s in the opposite direction.

5. Rearrange to solve for Procket
Solution
m1vi1 + m2vi2 = mrocketvrocket + mgasvgas
Initial Total Momentum Final Total Momentum
0 = Procket – 250 x 350
Rearrange to solve for Procket
Procket = 250x350 = kg*m/s
P=mv so… v = P/m = 87500/1050 = 83.3 m/s

6. Problem 3
Example A bird perched on an 8.00 cm tall swing has a mass of 52.0 g, and the base of the swing has a mass of 153 g. Assume that the swing and bird are originally at rest and that the bird takes off horizontally at 2.00 m/s. If the base can swing freely (without friction) around the pivot, how high will the base of the swing rise above its original level? Hints: How many objects due to have BEFORE the action? How many objects do you have AFTER the action?

8. YouTube!
Why does your coach tell you to follow through in tennis, golf, or baseball?
Why is foam placed around the Race Track and what variable does it change in the Impulse Equation?
What does it mean to say Momentum is Conserved?

9. Web Resources Momentum Misconceptions Physics Classroom Website