Flashcards in Centre of mass and moments Deck (9)

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1

## What is the centre of mass?

### the point on a object at which the mass of the object may be thought to be concentrated

2

## Where is the centre of mass on a symetrical object?

### along the axes of symettry

3

## How do you find the centre of mass by suspending the object?

###
drill a hole in the object and hang it so it is free to swing

hang a plumb line from the suspension point

marks the vertical line directly below the suspension point

hang it again in a different location and mark the vertical line

where the lines cross is the centre of mass

4

## What is a pendulum?

###
a plumb line is an example of a pendulum

the pendulum is free to swing

at the highest point of the swing there is no kinetic energy but maximum gravitational potentiol energy

while swinging, there is a high KE and low GP

e.g. playground swing, fairground rides

5

## What is a moment and what does the size of a moment depend on?

###
the turning effect off a force

size of force applied

perpendicular distance from pivot to the line of action of the force

6

## What are the moments on a object not turning?

### If an object is not turning, the total clockwise moment must be exactly balanced by the total anticlockwise moment about any pivot

7

## How do levers reduce the force needed to perform tasks?

###
levers rely on the principle of moments to act as force multiplies

the reduce the effort needed to move a load by increasing the distance over which the force is acting

8

## How can you calculate how to balance moments?

###
1) work out the moment for which you have been given all the infomation

2) change the subject of the equation to calculate the force

9