Module 4
PlanningGuide

Lab 1.14

Lesson 1.13
Lesson 1.14
Lesson 1.15
Lesson 1.16
Lab 1.13
Lab 1.14
Lab 1.15
Lab 1.16
Project 4

Physics Lab 1.14 Collisions - Marble & Chute

This experiment illustrates the vectors involved in collisions. When two objects collide and move off in different directions, the components of the vectors must add up to what they were before the collision.

1. Two bowling balls, one stationary and one moving and each with a mass of 5 kg, collide at an angle. The moving ball has a velocity of 0.8 m/s prior to collision.
   If, after collision, the second ball moves at 0.3 m/s at 30º to the direction of the first ball, what should the speed and direction of the first ball be after collision?

Physics Lab 1.14 Collisions

1. After the collision, momentum components in the direction of the collision and momentum components at right angles to the collision should be the same as before the collision.
   Before the collision, the ball has a momentum of 5kg x 0.8 m/s = 4 kg-m/s.
   After the collision, the second ball has a momentum in line with the original direction of the first ball of 5 kg x 0.3 x cos 30º m/s = 1.3 kg-m/s.
   The first ball should have a momentum with a component in its original direction of (4 – 1.3) kg-m/s
   = 2.7 kg-m/s
   The component of the momentum of the second ball at right angles to the original direction of the first ball = 5 kg x 0.3 x sin 30º = 0.75 kg-m/s. The first ball should have the same component in the opposite direction.
   The angle of the first ball will therefore be = tan^-1 (0.75 / 2.7) = 15.52º.
   Its velocity in this direction will be = 2.7 m/s / cos 15.52º
   This = 2.8 m/s.