FORCE

Force: a vector with the units - Newton (N).

"An object at rest tends to stay at rest and an object in motion tends to stay in motion;

A force is a push or a pull

unless acted upon by an unbalanced force."

F

When all forces acting on an object are , the motion of the object will NOT change.

Therefore - Unbalanced forces will cause the acceleration of an object (non-uniform motion).

balanced balanced Unbalanced

The more mass an object has, the more difficult it is to change the object’s state of motion - INERTIA

Changing motion means an acceleration.

Accelerating requires a force.

0 m/s 10 m/s

F

Newton's Second Law - relationship between an object’s mass and its acceleration.

Force = mass x acceleration

F = m a

Units: N = kg ms2

If the unbalanced force is in the same direction of motion, the object will speed up.

If the unbalanced force is in the opposite direction of motion, the object will slow down.

Acceleration of an object will always be in the same direction as the unbalanced force.

force motion

Acceleration = +10.0 m/s2

20 kg

Acceleration = + 5.0 m/s2

20 kg

Unbalanced Force (+100 N)

Unbalanced Force (+200 N)

Acceleration = +10.0 m/s2

50 kg

+ v

50 kg50 kg

50 kg 50 kg50 kg

Unbalanced Force (+500 N)

Unbalanced Force (-500 N)

Acceleration = -10.0 m/s2

If we apply a greater force, there will be a greater acceleration (either speeding up or slowing down).

The more massive an object becomes, the greater the force necessary to reach a certain acceleration.

F = ma

· As mass increases, so does inertia. (resistance to changes in motion)

· A unbalanced force on an object, causes acceleration of the object.

· The larger the unbalanced force applied, the larger the acceleration of the object.

· a larger mass requires a larger force to cause a constant acceleration.