Calculate Change in Momentum of Billiard Ball | CaptFormal

[CaptFormal]

Homework Statement

A billiard ball of mass m = 0.15 kg strikes the cushion of a billiard table at θ1 = 48° and a speed v1 = 21 m/s. It bounces off at an angle of θ2 = 670 and a velocity of v2 = 16 m/s. What is the magnitude of its change in momentum (in kg·m/s)?

http://schubert.tmcc.edu/res/msu/mmp/kap6/picts/pool.gif

Homework Equations

The Attempt at a Solution

Not sure how to solve this one. Any help will be appreciated.


CaptFormal

 

[rl.bhat]

Take the vertical and horizontal components of v1 and v2.
Find the difference in vertical and horizontal components. Take care of signs.Then take the resultant of these components.

 

[CaptFormal]

Ok, so here is what I got so far.

Vx = 21cos(48) - 16cos(67) = 7.8

Vy = 21sin(48) - 16sin(67) = 0.8779

Now I am not sure what to do. I tried the following:

(7.8^2 + 0.8779^2)^(1/2)

and then took that answer and multiplied it by the mass but it was incorrect. What am I missing?

 

[rl.bhat]

Vx = 21cos(48) - 16cos(67) = 7.8
This is wrong. vx components are in the opposite direction. So the change in vx is
Vx = - 21cos(48) - 16cos(67) = ?