Balanced and unbalanced forces

​Forces can act in 6 different ways...

• There are at least two forces acting on all objects at rest:

  • The objects weight due to gravity (pull towards the Earth)

Normal force (push from the surface holding the object up)​

Long Answer

Yes!

​Short Answer

Example: person “at rest”​

These forces are balanced (weight and normal force are equal)

The person is “at rest”.

If the chair could not balance the force of gravity she would fall through.​

Balanced forces​

For forces to be balanced then:

• The magnitude (size) of the two forces must be equal.

• The direction of the two equal forces must be opposite.

The objects motion will not change.​

Unbalanced forces​

When one force is bigger than another the forces are unbalanced.

This will cause:

• A change in motion 

  (start, stop, speed up or slow down)

• A change in direction

• A change in shape​

Start/Stop moving

Acceleration/deceleration

Change in shape/direction

​UNBALANCED

Constant speed

OR

At rest

​

BALANCED

Forward force from the pedalling is equal to the friction force pushing backwards.

The forces are balanced. 

The bike is travelling at a constant speed

without changing direction.

​To change the motion of the bike the rider must unbalance the forces by:

• Applying a brake force

• Applying less driving force than friction

• Applying a bigger driving force than the friction

​Buoyancy is an upward force produced by a gas or liquid.

• Buoyancy happens when an object is lighter than the gas/liquid.

​Net force is the total force acting on an object.

• Add the forces when they operate in the SAME direction.

Subtract the forces when they operate in DIFFERENT directions.