# physics p3 moments

just explainng it

HideShow resource information
• Created by: Hannah
• Created on: 22-05-11 06:24

## Turning effects

trying to suncrew a nut requoires a spanner, it is common knowledge that the LONGER TH SPANNER the easier it is - this is becasue LESS force is required.

Unscrewing this nut is known as a turning force and the turning effect of the force is called the moment.

This can be increased by:

• increasing the size of the force
• using a longer instrument

the push is of the force applied is called effort when trying to ift ofjects, the LOAD around the PIVOT

equation =

MOMENT = FORCE X PERPENDICULAR DISTANCE FROM PIVOT

1 of 4

## centre of mass

the centre of mass is that there is a point of an object where we can think of it as though the weight ACTS A THAT SINGLE POINT

a hanging object rests with its centre of mass directly below the pointo of suspension. This means it is said to be in EQUILIBRIUM , no turning force is exerted by the weight

when the object moves it is NON - EQUILLIBRIUM

2 of 4

## stabity

• if you tilt a brick slightly - and then release it the turning effet of the brick weight returns it to the upright position
• if you tilt the brick just a bit further, if the centre of mass is directly in side still, then the box will not fall
• howevewr if you tilt the brick and the centre of mass is outside the box it will tip over

TRACTORS

they hav wheels that are very wide apart and the engines are very low to the ground.

the centre of mass is in the engline

so it would be safe on very seep edges

ALSO SIMILAR FOR BUSES AND COACHES - tight corners - hilly roads

3 of 4

## circular motion

an object attached to a piece of string or similar material when wirled around, will move in a CIRCULAR MOTION

for an object moving at a constant speed at aby instant

• its velocity is directed along tangent  to the circle
• the veloity is ALWAYS changing as it moves around
• the change of the velocity is toward the centre of the circle

therefore the object is always accelerating towards the centre of the circle, the force on the object is called the CENTRIPETAL FORCE and always acts toward the centre of the circle

4 of 4