University:
California Institute of Technology
Course:
EE/APh 40 | Physics of Electrical Engineering
Academic year:

2019
Views:

339

Pages:

10
Author:

StellarStrategist

Momentum is conserved for all collisions as long as external forces don’t interfere. The concept of inertia was introduced and developed both in terms of objects at rest and objects in motion. In this chapter we are concerned only with the concept of inertia in motion— momentum. 8.1 Momentum A moving object can have a large momentum if it has a large mass, a high speed, or both. 8.1 Momentum It is harder to stop a large truck than a small car when both are moving at the same speed. The truck has more momentum than the car. By momentum, we mean inertia in motion. 8.1 Momentum Momentum is the mass of an object multiplied by its velocity. momentum = mass × velocity momentum = mv When direction is not an important factor, momentum = mass × speed 8.1 Momentum • • • A moving truck has more momentum than a car moving at the same speed because the truck has more mass. A fast car can have more momentum than a slow truck. A truck at rest has no momentum at all. 8.1 Momentum A truck rolling down a hill has more momentum than a roller skate with the same speed. But if the truck is at rest and the roller skate moves, then the skate has more momentum. 8.1 Momentum think! Can you think of a case where a roller skate and a truck would have the same momentum? 8.1 Momentum think! Can you think of a case where a roller skate and a truck would have the same momentum? Answer: The roller skate and truck can have the same momentum if the speed of the roller skate is much greater than the speed of the truck. For example, a 1000-kg truck backing out of a driveway at 0.01 m/s has the same momentum as a 1-kg skate going 10 m/s. Both have momentum = 10 kg•m/s. 8.1 Momentum What factors affect an object’s momentum?

Momentum Lecture 1

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