Momentum and Impulse Flashcards
Momentum?
An indication of how hard it is to stop a moving object. Understand that because momentum is calculated as the product of mass and velocity, if any of those two factors change, momentum will change in response.
Linear Momentum?
The product of the mass and velocity of an object.
Impulse?
The product of the net force and the time for which it acts.
Impulse-Momentum Theorem?
Simply the understanding that impulse is equal to the change in momentum because of its equation.
System?
Any group of objects.
Internal Forces?
Forces exerted by the objects in the system on each other.
External Forces?
Outside forces exerted on the system.
Isolated System?
No net external forces acts on the system. This could be friction, even air friction.
Law of Conservation of Linear Momentum?
The total linear momentum of an isolated system remains constant and is conserved. State this at the beginning of every question based on momentum.
Elastic Collision?
A collision in which both momentum and Kinetic Energy are conserved. All collisions involving gas molecules colliding with gas molecules are perfectly elastic.
Inelastic Collisions.
A collision in which only momentum is conserved. All everyday collisions are inelastic and this involves objects sticking together. The energy lost is just energy that went into (mostly) deformation, heat and sound.
Describe the effects of Fres being in the same direction as motion? Give an example.
Speed increases and direction of motion stays the same. Momentum’s direction therefore stays the same and magnitude increases, (Δp is +) Ex: Firing 2cd stage of engine rocket.
Describe the effects of Fres being in the opposite direction to original motion? (Small Magnitude) Give an example.
Speed decreases but direction of motion stays the same. Therefore, momentum direction is the same but magnitude decreases, (Δp is -). Ex: Applying brakes but not enough to stop the car.
Describe the effects of Fres being in the opposite direction to original motion (Big Magnitude). Give an example.
Speed decreases, becomes zero and then increases in opposite direction. Therefore momentum direction changes, (Δp is -) Ex: bouncing a ball against a wall.
