# This investigation is about what factors affect friction.

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Introduction

## INTRODUCTION

This investigation is about what factors affect friction.

What is friction?

Friction is a stopping power. The scientific definition of friction is:

Friction is a force, which opposes the direction of a movement of an object… and acts when an object moves through a medium e.g. water, air or when surfaces slide past each other.

## EXAMPLES OF HOW FRICTION WORKS

When a motor vehicle is moving at a steady speed, the frictional forces exactly balance the driving force. However, friction causes objects to HEAT UP and WEAR AWAY at their surfaces. Oil is required where surfaces move against one another

Friction is also useful in many ways.

- Between a vehicle tyre and the road surface
- Between brake pads and brake discs

If the braking force applied is great, the friction between the tyres and the road may not be great enough to prevent skidding.

The factors that can be changed (the variables) are the following:

- Weight
- Type of surface
- Speed
- Surface area
- Lubrication

REMEMBER: IF THERE IS MORE FRICTION YOU WILL NEED MORE FORCE TO MOVE THE OBJECT.

Now I will describe how each factor affects friction.

## SPEED

SLOW BIGGER GRIP BIGGER FRICTION

FAST SMALLER GRIP SMALLER FRICTION

If the car speed is slow, there will be a bigger grip between the tyre and road.

Middle

## PREDICTION

My prediction for this investigation is that; the more the weight of the object, the more force will be needed to move the object because when you put more weight it makes 2 surfaces grip together with more force.

I predict that as the weight increase, the force will also increase. Therefore the weight should be directly proportional to the force. My graph should be similar to the one below. I also predict that if I double the weight the force should also double.

## DOING THE INVESTIGATION

APPARATUS needed for this investigation.

- A block of wood (with a hook)
- Weights
- Newton measurer
- Weight measurer
- Flat surfaced wood -to do experiment on.

## RISK ASSESSMENT

The safety precautions I need to take for this investigation are THAT I MUST MAKE SURE THAT I DON’T LET THE SPRING SNAP (NEWTON MEASURER).

## Trial results

Before I did the actual experiment, I did trial results, which consisted of the first three set of weight to see if there is a pattern in my results.

Weight (N) | Trial 1 | Trial 2 | Trial 3 | Average |

2.6 | 0.9 | 0.8 | 0.9 | 0.86667 |

3.6 | 0.2 | 0.4 | 0.5 | 0.36667 |

4.6 | 1.6 | 1.6 | 1.7 | 1.63333 |

5.6 | 2 | 2.2 | 1.7 | 1.96667 |

From the trial results you can see that the first weight (N) that I started off with was 2.6N. This was the weight of the block of wood with the hook.

How I converted the weight into Newtons?

Conclusion

But in my prediction I also said that if I double the weight the force should also double. I cannot say if it did by looking at my results table because if I double 2.6N I will get 5.2N. 5.2N is not a value that I investigated, so to prove this theory I will have to look at the graph to see if my theory is correct.

After looking at the graph I know that the force needed to pull:

2.6N is 0.85N

5.2N is 1.675N

so as you can see that roughly, as I doubled 2.6N, the force also doubled. But to make sure that this is not a coincidence, I will look at the graph and see if the force double as I doubled 4N.

The force needed to pull

4N is 1.3N

8N is 2.6N

This means that my theory is correct because as I doubled the weight of 4N, the force needed to move the weight also doubled.

Overall, my prediction was right because the weight is directly proportional to the force and also as the weight doubles, the force also doubled.

## EVALUATION

From this experiment I can say that:

The more the weight, the more the friction therefore more force will be needed to move the object.

Name: Razwana Bi

Form: 11.4

Broadway School

Centre number: 20049

Candidate number: 0049

Plan and carry out an investigation to find out what factors affect friction.

This student written piece of work is one of many that can be found in our GCSE Forces and Motion section.

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