• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month
Page
  1. 1
    1
  2. 2
    2
  3. 3
    3
  4. 4
    4
  5. 5
    5
  6. 6
    6
  7. 7
    7
  8. 8
    8
  9. 9
    9
  10. 10
    10
  11. 11
    11
  12. 12
    12
  13. 13
    13
  14. 14
    14
  15. 15
    15
  16. 16
    16
  17. 17
    17
  18. 18
    18

Investigation into Friction.

Extracts from this document...

Introduction

Investigation into Friction

Aim

Our aim is to investigate the relationship between the frictional force between two surfaces, and the force needed to make the surfaces slide over one another. The investigation will also be into the type of surface and the amount of frictional force, and the force needed to make the surfaces slide. We will also be investigating the coefficients of friction on different surfaces.

Theory

Friction is the name given to the force, which opposes the relative sliding motion of two surfaces in contact with one another, as Ordinary Level Physics[1] by AF Abbott tells us. This means that when two objects slide over one another, or touch one another, there is a frictional force present that tries to stop any sliding movement. The attractive forces between the molecules on the two surfaces cause friction, the Ordinary Level Physics says. Fig 1[2] shows two surfaces, and the cause of friction between them. The surfaces are not totally smooth, and so the particles oppose the forward movement of the others, and are also attracted to each other, causing friction.

image00.png

Fig 1.

        The more force there is acting on the surfaces, the more friction there is. This means that if there were a force of 10 N acting on the top surface, the friction would be greater than if no force other than gravity were acting on the top surface. There is also less friction between two surfaces if there are less ‘rough’ places for friction to occur. This means that if the two surfaces were smooth, there would be less frictional force acting than if they were both rough surfaces. Therefore, the smoother the surfaces, the less resistance there is to movement due to friction. Also, the more force there is acting on surfaces, the greater the frictional forces between them.

...read more.

Middle

Force meter calibrated in NewtonsString

Method

  1. The apparatus was set up as shown in Fig 2.
  2. The smooth hardboard was used first as the bottom surface.
  3. Weights were added to the wooden block 10 N at a time.
  4. The force meter was used to make the block move along the smooth hardboard.
  5. The reading on the force meter was taken at the moment when the block moved.
  6. This was repeated immediately for each weight.
  7. The experiment was repeated using the rough hardboard as the bottom surface.
  8. The results were recorded in Tables 2 and 3.

Results

Smooth hardboard

Added mass / kg

Total mass / kg

Total weight / N

Reading on force meter (F) / N

1st exp

2nd exp

Average

1.0

1.328

13.28

5.5

6.0

5.75

2.0

2.328

23.28

9.5

10.0

9.75

3.0

3.328

33.28

13.5

13.0

13.25

4.0

4.328

43.28

15.0

17.0

16.00

5.0

5.328

53.28

21.0

17.0

19.00

6.0

6.328

63.28

23.0

24.5

23.75

7.0

7.328

73.28

25.0

30.0

27.50

Table 3.

Rough hardboard

Added mass / kg

Total mass / kg

Total weight / N

Reading on force meter (F) / N

1st exp

2nd exp

Average

1.0

1.328

13.28

5.0

4.5

4.75

2.0

2.328

23.28

8.0

8.5

8.25

3.0

3.328

33.28

13.0

13.5

13.25

4.0

4.328

43.28

18.0

18.0

18.00

5.0

5.328

53.28

22.0

22.0

22.00

6.0

6.328

63.28

23.0

24.5

23.75

7.0

7.328

73.28

25.0

25.0

25.00

Table 4.

Observations

When we did the experiment, we discovered that the force taken to make the masses move on the second reading on the smooth hardboard was greater than the preliminary experiment predicted. When the weight added was 70 N, the force needed to make the burden move was 30 N for the second reading. This meant that the following masses would be too heavy for it to only take 30 N to move them. The experiment for the smooth hardboard was then only continued to an added weight of 70 N.

Analysis of Results

The masses added in the smooth surface experiment did not reach 93.28 N, as predicted. This could have been because the surfaces were not exactly the same throughout the experiment, and so when it came to adding 90 N to the block, the surface had been changed significantly enough for the frictional force to have increased. Also, the place where the preliminary experiment was done could have been different to the place where the actual experiment took place.

...read more.

Conclusion

Improvements to provide additional evidence

If the pressure sensor was used, the coefficient of dynamic as well as static friction could be investigated. Using the method described above, when the block touched the pressure sensor when it just started to move, the data logger would record the force needed. But because the pressure sensor is moveable, after the block has touched it, if the block kept being pulled, the pressure sensor would come with the block. This would mean that the force needed to keep the block and weights moving could be recorded. This could be used to give us the coefficient of dynamic friction, and we could then compare the two coefficients of static and dynamic friction, on different surfaces.

        We could also investigate how the speed at which the force at F is applied affects the coefficient of friction for different surfaces. This would be done by pulling the burden at different speeds. To make sure that the speed was regular, markings could be made on the board, indicating the position that the burden needed to be in after a certain time. For instance:

speed = distance ÷ time

If the speed was to be 0.001 m/s, then the block will have to have moved 1 cm in 1 second, 2 cm in 2 seconds etc. The centimetres could be marked on the hardboard, and the ‘puller’ would have to pace himself so that the block was passing the centimetre mark on the second. This method could be used for any speed. The affect that the speed that force is applied at could then be investigated, extending the original experiment.    

Graphs

image02.jpg

Graph 1.

image03.jpg

Graph 2.        

image02.jpg

Graph 3.

image03.jpg

Graph 4.


[1]Ordinary Level Physics; AF Abbott; page 17

[2] Microsoft Encarta 96 Encyclopaedia

[3]Letts GCSE Physics Classbook; Graham Booth; page 58

[4]Ordinary Level Physics; AF Abbott; page 18

[5]Ordinary Level Physics; AF Abbott; page 18

...read more.

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

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related GCSE Forces and Motion essays

  1. Mechanics 2 Coursework - 'woosh' down the slide

    The experiment will be conducted using H = 0.283m and at a angle 30�to make a start. Then will do 35 and 40 degrees. 5 different lengths for each angle. This will hopefully obtain a good set of results. I then got the results as below: ?(�) ?(�) L(m) H(m)

  2. In this experiment I aim to find out how the force and mass affect ...

    Manually timing the experiment: Added weight (g) Time taken to travel 2m (s) Velocity [distance/time] (m/s) Average speed (m/s) 0 3.51 3.44 3.32 0.64 0.58 0.61 0.61 200 2.33 2.17 2.13 0.86 0.92 0.94 0.91 400 2.26 2.15 2 0.88 0.93 1 0.94 600 2 2.15 2.16 1 0.93 0.93

  1. Approximate Stopping Distances

    Car accidents are happening everyday at an increasing rate therefore braking distance is a vital part of scientific research. This is because modern cars are becoming faster and there are too many vehicles on roads. As velocity decreases so does the distance it takes to stop the vehicle.

  2. The Helicopter Investigation

    1.10 m/s 1.45 m/s 4cm 1.44 m/s 1.32 m/s 1.42 m/s 1.39 m/s 3cm 1.19 m/s 1.14 m/s 1.18 m/s 1.17 m/s 2cm 1.03 m/s 1.02 m/s 1.08 m/s 1.04 m/s My results show major anomalous result through Test 1 & 2, however throughout the averages this becomes very minor

  1. Mechanical Properties of a Meter Rule

    After this limit has been exceeded, the size and shape of the specimen after removal of the load will not be the same as before, and the difference or amount of change is known as the ~permanent set~. Elastic limit as measured in tests and used in design may be

  2. What affects the frictional force between sliding surfaces?

    Hypothesis/Prediction I predict that as the weight of the object increases so will the frictional forces, which will also increase the pulling force, therefore making the weight of the object, frictional force and the pulling force directly proportional. Predicted Graph Preliminary Work I choose my range and equipment based on

  1. Investigating Sliding Friction: the effect of weight on sliding friction between a block and ...

    I have chosen foam because it gave me the best range of results. From a good range of results I will be able to draw a clearer conclusion. As well as foam, polystyrene gave a good range of results but the piece of polystyrene I had was too small, because

  2. Strength of a string practical investigation

    * Do not alter the position of G-clamp, Pulley, metre rule, wooden blocks and table during all the experiments have been completed * All string must be manufactured from the same company and come from the same batch. All the same equipment must be used every time experiment is carried

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work