Momentum 1

MLearner mobile

your portal to mobile learning

Momentum 1
Have you noticed how a moving object can cause you fear?
Imagine a cricket ball moving towards you quite fast!
You've got to leap out of the way! A full shopping trolley rolling towards you is more dangerous than an empty trolley rolling towards you.
So scientists came with up with a concept called MOMENTUM.
Momentum is the “quantity of motion” of an object.
It is the product of the mass and velocity of an object.

Some MOMENTUM facts:
a. Momentum is a vector quantity. So your answer to a question must include a number and a direction.
b. The symbol for momentum is p.
c. The equation to calculate momentum is p = mv
d. The unit for momentum is kg.m.s^-1

Examples
It is best to learn by doing some examples.
1. A trolley of mass 2kg is moving at a velocity of 3ms^-1 east. Calculate its momentum.
p = mv
p = (2)(3)
p = 6kg.m.s^-1 east

2. A trolley X of mass 6kg has a velocity of 5ms^-1 west.
Calculate it’s momentum.
p = mv
p = (6)(5)
p = 30kg.m.s^-1

3. The momentum of a wooden cart is 18kg.m.s^-1 east. It has a velocity of 6m.s^-1.
3.1. It which direction is it moving?
east
3.2. What is its mass?
p =mv
18 = m(6)
m = 3kg

4. A trolley X of mass 6kg has a velocity of 4ms^-1 .
4.1. Calculate it’s momentum.
p = mv
p = (6)(4)
p = 24kg.m.s^-1

4.2. At what velocity should a trolley Y of mass 12kg travel in order to have the same momentum as X?
p = mv
24 = 12v
v = 2m.s^-1