Ch. 7 Momentum by emily esser

Ch. 7 Momentum

Linear Momentum

vector Quanity having same direction as the velocity

The vector of p = mass times the vector of velocity

The momentum and changes of two objects are always equal and opposite

Momentum

Vector quanity

For momentum to be Conserved these things must be constant

Magnitude

Direction

Mass and velocity involved

Conservation

If no external force acts on system, the initial momentum of the system is equal to the final momentum of the system.

Collisions

Completely Inelastic

“Perfect Sticking”

Conservation of only momentum

m1v1i +m2v2i = (m1 +m2 )vf

Inelastic

“Sticky” but the bodies do not stick together

Conservation of momentum only

Elastic

“Perfect bouncing”

Conservation of kinetic energy and momentum

m1v1i +m2v2i = m1v1f +m2v2f

System of Particles

Center of Mass

Average location of the mass in a system of particles

3D in general

Motion of the Center of Mass

Isolated system moves at a constant velocity

Problem solving: Collisions

Draw before and after diagrams

Collect and organize data on masses and velocities

Set the sum of momenta of the two before the collision = to the sum of the momenta after the collision

Write one equation for each direction

If perfectly inelastic set final velocities equal

If perfectly elastic set final kinetic energy equal to initial kinetic energy

Solve for unknown quantities

Words of the Day

Transpicuous

Trust

Woolgathering

Applicability