Question

Need help with momentum and calculations

Two physics 7B students are testing the laws of physics on ice, where friction is negligible. Initially Manuel is skating East with momentum of 100 kgm/s. He is also holding a ball which weighs 5 times less than him (m_M = 5m_b). Jaz is skating West with initial momentum of 120 kgm/s. She weighs four times more than the ball (m_J = 4m_b). Initial conditions are draw here. When filling in the momentum charts make sure to draw an arrow and write x- and y- components for each box in the chart. A complete chart will serve as your explanation. a) Manuel throws the ball giving it an impulse of 50 kgm/s in the North direction. Fill in the momentum chart for Manuel throwing the ball. Calculate the magnitude of the final momentum of the ball. b) After Manuel throws the ball as described in a), Jaz catches it. Fill in the momentum chart for Jaz catching the ball.

Answer 1

let i and j are unit vectors along +ve x and +ve y axis.
part a:

initial momentum of manuel is 100 kg.m/s to the east.

when he throws a ball is 50 kg.m/s in north direction.

so delta_P=-50 j kg.m/s

final momentum of manuel=100i -50 j

so table will look as below:

system	p_i	delta_p	p_f
manuel	100 i	-50 j	100 i - 50 j
ball	0	50 j	50 j
total	100 i	0	100 i

part b:

system	p_i	delta_p	p_f
jaz	-120 i	50 j	-120 i+50 j
ball	50 j	-50 j	0
total	-120 i + 50 j	0	-120 i + 50 j