Turning Forces and Centre of Gravity Chapter 43

Turning Forces and Centre of Gravity Chapter 43

A Lever • A lever is a rigid body which is free to turn about a fixed point called the fulcrum. • Example: – Crow bar – Wrench

The Moment • The moment of a force tells us how much spin or circular motion a force can cause. Moment of a Force x Perpendicular distance from the force to the fulcrum

Law of the Lever • The law of the Lever states that when a lever is balanced the sum of the clockwise moments equals the sum of the anticlockwise moments.

The Law of the Lever

Centre of Gravity • The centre of gravity is the point of an object where all the forces appear to act.

Equilibrium • Equilibrium is when an object is balanced and not moving. • 3 states of equilibrium: – Stable equilibrium – Unstable equilibrium – Neutral equilibrium

Stable Equilibrium • If given a slight push the object will return to the same position.

Unstable Equilibrium • If given a slight push the object will not return to the same position.

Neutral Equilibrium • If given a slight push the object will return to a similar position.

Stability • An object will topple over if its centre of gravity passes outside its base.

Stability • Objects are more stable if they have: – A wide base – Low centre of gravity • Examples – Bunsen – Bus – Flower vase