- Level: International Baccalaureate
- Subject: Physics
- Word count: 1477
Research question: Part A : What is the static friction coefficient of a certain surfaces that are in contact? Part B : What is the kinetic friction coefficient of a certain surfaces that are in contact?
Extracts from this document...
Introduction
NAME
MOHD SUKRI BIN ISMAIL
PARTNER
FIKRI AKMAL MOHD SALLEH
CLASS
E03F
DATE
September 6th, 2004 and September 14th, 2004
TITLE
INVESTIGATION OF THE ROUGHNESS OF TWO SURFACES IN CONTACT
(friction)
Abstract:
This experiment is conducted in two different parts; part A is the determination of the static friction coefficient whilst part B is the determination of the kinetic friction coefficient. In part A, after the apparatus are set up as shown in the diagram, the length of the wood plane used as the track is measured. Then, the plane is elevated gradually at one of its end. The plane is held still using a retort stand when the block rested on the plane is moving, in order to reduce the error in measuring the height of the elevated end of the plane from the desk surface. The experiment is then repeated by using different surfaces which were between glass/wood and wood/sand paper. The value of the static friction coefficient is calculated by using the formula of = tan or by using the ratio of the height of the elevated end of the plane to the horizontal length of the plane. From the experiment, it can be determined that the static coefficient for wood surface with wood surface is 0.454, glass and wood is 0.315 while the sand paper surface with wood is 0.785.
Middle
Horizontal length, cm
Coefficient,
Wood / wood
31.4
69.2
0.454
Wood / sand paper
14.2
18.1
0.785
Wood / glass
5.7
18.1
0.315
Uncertainty;
e.g
Surfaces | Coefficient, |
Wood / wood | 0.454 |
Wood / sand paper | 0.785 |
Wood / glass | 0.315 |
Part B;
F = ma
mg sin - = ma
Through out the experiment, the angle of the elevation is fixed at 30.
Determination of the acceleration of the block;
e.g Surface; wood / wood
initial velocity, u = = cms-1
final velocity, v = = cms-1
Conclusion
- In determining the coefficient of the static friction, the formula of = tan can be used. Nevertheless, since the method used in this portion of experiment allows the experimenter to choose between two options which are either to use the above equation of to use the ratio of the height of the elevated end of the plane to the horizontal length of the plane. The experimenter choose to use the ratio as error is minimized, compared to the equation.
Conclusion:
Part A : The greater the coefficient, the rougher the surfaces. The coefficients are different between different surfaces. This is due to the fact that if the object is having bigger angle of inclination, it shows that the coefficient is bigger. Thus, it can be concluded that the surfaces are rougher.
Surfaces | Coefficient, |
Wood / wood | 0.454 |
Wood / sand paper | 0.785 |
Wood / glass | 0.315 |
Part B : The greater the coefficient, the rougher the surfaces. The coefficients are different between different surfaces. This is due to the fact that if the object is having bigger force to be applied in order to move it, it shows that the coefficient is bigger. Thus, it can be concluded that the surfaces are rougher.
Surfaces | Coefficient, |
Wood / wood | 0.3290 |
Wood / sand paper | 0.4780 |
Wood / glass | 0.2390 |
Contribution:
- I suggested to use the acceleration method to determine the kinetic friction
- I recorded the results obtained.
- I elevated the track.
References:
- http://hyperphysics.phy-astr.gsu.edu
This student written piece of work is one of many that can be found in our International Baccalaureate Physics section.
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