Physics - 10 Force and Motion - 10.4 Momentum & 10.5 Using Conservation of Momentum & 10.6 Impact Forces

Momentum

product of an object's mass and velocity

Momentum =

mass x velocity

p =

mv

Unit of momentum

kilogram metres per second, kg m/s

Closed system

system in which matter and energy exchanges do not occur across boundaries

Conservation of momentum

total momentum of a system remains constant when there are no net external forces acting on it

... is conserved after a collision or explosion

momentum

After an explosion, objects recoil with ... momentum

equal and opposite

Momentum is a (vector/scalar) quantity

vector

In a controlled explosion:

(mass A x velocity A) = -(mass B x velocity B)

Crumple zone

region of a vehicle designed to absorb the energy of impact

What does a crumple zone do?

increases impact time hence decreases force

As impact time increases...

impact force decreases

Impact force is equal to...

change in momentum per second

a =

∆v ÷ t

F =

ma

impact force =

(mass x change in velocity) ÷ time

(impact) F =

(m∆v) ÷ t