P5 FORCES (moments, levers and gears)

What may a force or a system of forces cause an object to do?

Causes an object to rotate.

Describe two examples in which forces cause rotation

When a door handle is pushed down it causes it to rotate about a pivot.

A spanner is pushed down, it causes it to rotate to turn a nut at the pivot.

What is the moment of a force?

The moment of a force is the turning effect of the force

What is the size of a moment defined?

Product of the force and the perpendicular distance from the pivot to the line of action of the force.

What are the units of the moment of a force?

Newton metres

If an object is balanced, what is the relationship between the total clockwise moment and the total anti clockwide moment about a pivot?

The total clockwise moment equels the total anti clockwise moment.

What can be used to transmit the rotational effect of forces?

A simple lever and a simple gear system

What are gears?

Circular disks with interlocking teeth around their edges which rotate about axles

How do levers transmit the rotational effects of forces?

By Increasing the perpendicular distance from the pivot where a force is applied to the load.

Causing a larger force to act upon the load than is applied to the lever

How do gears transmit the rotational effects of forces? (8)

Gears transmit the rotational effect of forces as the forces acting on their teeth are equal (1)

-a force transmitted to a larger gear will cause a greater moment (1)

-as the perpendicular distance from the pivot is greater (1)

-and the larger gear will rotate more slowly (1)

-a force transmitted to a smaller gear will cause a smaller moment (1)

-as the perpendicular distance from the pivot is shorter (1) ,-and the smaller gear will rotate more quickly (1)

-the two gears always rotate in opposite directions (1) .