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Conservation of Momentum. The net momentum of an isolated system cannot change . Isolated no net external force is applied. Momentum before equals momentum after. p i = p f. Rockets are able to move in the nothingness of space because of this.
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The net momentum of an isolated system cannot change. • Isolated no net external force is applied. • Momentum before equals momentum after. • pi = pf
Rockets are able to move in the nothingness of space because of this. • Gas is expelled at high velocity, causing the rocket to move forward.
Example 1 • A 76 kg boater, initially at rest in a stationary 45 kg boat, steps out of the boat and onto the dock. If the boater moves out of the boat with a velocity of 2.5 m/s to the right, what is the final velocity of the boat?
Inelastic Collisions • The objects stick together after the collision. • Ex: guy jumping on skateboard, tackling someone.
Kinetic energy IS NOT conserved in an inelastic collision. • Usually goes into thermal energy…i.e., HEAT.
Elastic Collisions • Bounce off each other, no loss in kinetic energy.
Realistically, there are no purely elastic or inelastic collisions. • They’re ideals.