Flashcards in FM1 - Turning forces, centre of gravity and moments Deck (15):

1

## What is a moment?

### The turning effect of a force

2

## What is the equation linking moment, force and distance?

###
Moment(Nm) = Force(N) x perpendicular distance (m) (between line of action and pivot)

3

## Explain what happens with a spanner and a nut (force? moment?)

### The force on the spanner causes a turning effect or moment on the nut. A larger force would mean a larger moment

4

## What happens if you use a longer spanner (same force as smaller spanner but different distance) ?

### Exerts a larger moment because the distance from the pivot is greater

5

## What do you need to do to get the maximum moment?

### Push at right angles to the spanner

6

## Why cant you push at any other angles?

### It means a smaller moment because the perpendicular distance between the line of action and the pivot is smaller

7

## Where does the centre of gravity hang directly below?

### The point of suspension

8

## What is the centre of gravity of an object?

### The point at which the weight of the body acts

9

## When will a freely suspended object stop swinging?

### When it is vertically below the point of suspension - no moment as the pivot is in line with the line of action of the force

10

## Describe how you can find the centre of gravity of any flat shape using a plumb line

###
1) Suspend the shape and a plumb line from the same point and wait to until they stop moving

2) Draw a line along the plumb line

3) Do the same again but suspend shade from different pivot point

4) The centre of gravity is where the two lines meet

11

## How can you work out the centre of gravity for simple shapes eg a square?

### Look at the lines of symmetry (where two lines cross in the middle is the c.og)

12

## What is the principle of moments?

###
Total anticlockwise moments = Total clockwise moments

(When acting in a balanced object)

13

## *Why do you ignore the weight of a seesaw when working out a question?

### Its centre of mass is on the pivot, so it does have a turning effect

14

## If a light rod (when you ignore weight in the calculations) is being supported at both ends, will the upwards force be the same?

### No - if a heavy object is placed on the rod, the support closest to the object will provide a larger force

15