Collisions in Two Dimensions:
Glancing Collisions
Learning Goals
• analyse, in qualitative and quantitative terms, the relationships between mass, velocity, kinetic
energy, momentum, and impulse for a system of objects moving in one and two dimensions
(e.g., an off-centre collision of two masses on an air table, two carts recoiling from opposite ends
of a released spring), and solve problems involving these concepts
Glancing collisions
▪ A glancing collision is when the impact between two objects is imperfect
▪ This means that the centers of the object are out of alignment
▪ The result of a glancing collision is the momentum exchange is at an angle to
the original motion. And the objects veer off at angles
▪ Laws of conservation are still in effect
▪ However calculations will have to include x-y components
Components of momentum
▪ In previous lessons when discussing changes in momentum we were only
searching for one unknown, the final velocity.
▪ But in a glancing collision we now have two unknowns, the x and y
components of velocity
Ex 1. A large meteor of mass 1.25 x 106 kg travelling at
4.1 km/s [towards sun] suddenly detonates into 3
pieces as shown.
Ex 1. A large meteor of mass 1.25 x 106 kg travelling at
4.1 km/s [towards sun] suddenly detonates into 3
pieces as shown.
Fragment 1: 0.25 x 106 kg 6.5 km/s [38o up from horiz]
Fragment 2: 0.31 x 106 kg 8.5 km/s [23o up from horiz]
Calculate the momentum and velocity of the third piece
Solution:
 Since the net force on the meteor is zero, the p before the explosion
must equal the p after the explosion.
 This means that the p of all the fragments must equal the initial p of
the meteor.
2.635x109 kg m/s
23o
1.625x109 kg m/s
p3
38o
5.125x109 kg m/s
 Solving for the momentum of the third piece we get:
2.5x109 kg m/s [55o down from horizontal]
3.6 km/s [55o down from horizontal]