Momentum and Newton’s 2nd Law of Motion

MomentumMomentum - an object’s

tendency to keep moving Determines how difficult it is to

stop the object’s motion

Formula: Momentum = Mass x Velocity

MomentumMomentum = mass x velocity

Momentum = 1.5-kg x 10m/s2

Force = 15 kg-m/s2 or 15 N

A 1.5-kg ball is thrown at 10 m/s2. What is the ball’s momentum?

MomentumExample:

A 100-kg fullback runs up the middle of the football field. He collides with a 75-kg defensive back running toward him. The more massive fullback is thrown back two meters. Although he has less mass, the defensive back has more momentum because he is moving faster than the fullback.

Momentum

Law of Conservation of Momentum - the total momentum of any group of objects remains the same, unless outside forces act on the objects.

Newton’s Second Law

An object’s acceleration depends on its mass and on the net force acting on it.

Formula:Net Force = Mass x Acceleration

or

F = ma

Newton’s Second Law

Force = mass x

acceleration

Force = 1700kg x 2m/s2

Force = 3,400 kg-m/s2 or 3,400N

How much force is needed to accelerate a 1,700 kg car 2 m/s2?

Newton’s Second Law

An object will have greater acceleration if a greater force is applied to it.

Example: If you push a child on a swing, the swing begins to move. The harder you push, the faster the swing accelerates.

Newton’s Second Law

The mass of an object also affects the acceleration of the object.

In other words:If it’s big, it’s going

to move slow

If you push it harder it is going to go farther

Newton’s Second Law

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