Momentum

“Inertia In Motion”

Physics

Record:

• p = mv

• p(before) = p(after)

• impulse = I = Ft

• impulse = I = change in momentum = Dmv

• momentum is a vector (direction matters)

California State Standards

Physics: Conservation of Energy and Momentum 2. The laws of conservation of energy and momentum

provide a way to predict and describe the movement of objects. As a basis for understanding this concept:

d. Students know how to calculate momentum as the product mv.

e. Students know momentum is a separately conserved quantity different from energy.

f. Students know an unbalanced force on an object produces a change in its momentum.

g. Students know how to solve problems involving elastic and inelastic collisions in one dimension by using the principles of conservation of momentum and energy.

Momentum

• Momentum is “inertia (mass) in motion”

• Formula: p = mv

• Momentum is a vector (size & direction)

• Momentum is conserved (in a closed system)

• mv = mv (a roller skate can have the same

(or more) momentum as a cement truck!)

Force x Time = Change in Momentum

Impulse • Impulse is force applied for a period of time(Ft)

• Impulse changes momentum F = ma

a = Δv / Δt

F = m(Δv / Δt)

F Δt = m(Δv) = Δ(mv)

I = Ft = Δ(mv) (impulse = change in momentum)

• A change in momentum requires an impulse (Newton’s 1st Law!)

• Ft = Ft

Impulse = Change in Momentum

Momentum and Impulse

Collisions: Elastic and Inelastic

Inelastic Collisions Pbefore = Pafter (conservation of momentum)

End