JA509 Engineering Laboratory 1EXPERIMENT

:EL3 -1

TITLE:FRICTION (INCLINED PLAIN)

DURATION:6 HOURS

PAGE:1 0F 4

1.0 Experiment outcomesAt the end of the lab session students should be able:

a) Determination of the friction coefficient for different materials.

b) Force on the incline plane for different materials.

2.0 Theory

When a body slides over another, the motion resisted by a force called the friction force. The force arises from the fact that the surfaces, though planed and made smooth, have ridges and depressions that interlock and relative movement is resisted. Thus the force of friction on a body is parallel to the sliding surfaces and acts in a direction opposite to that of the sliding body.

Friction coefficient ;

Static friction coefficient from figure 1.1 ;When a body is a rest on an inclined plane making an angle with the horizontal, the forces acting on the body in figure 1.2

Upward motion the plane equation is given , P =W (sin + cos )

Downward motion the plane equation is given , P = W ( cos - sin )

3.0 Apparatus/Equipmentsi. Incline plane mechanismii. 2 material combination ( steel, brass, polypropylene and aluminium)iii. A Weight setiv. A Graduated angle scalev. The Support columnvi. The base plate

4.0 Safety Precautionsi. Perform only those experiments authorized by your instructor. Carefully follow all instructions, both written and oral. Unauthorized experiments are not allowed.ii. Be prepared for your work in the laboratory. Read all procedures thoroughly before entering the laboratory. Never fool around in the laboratory.iii. Observe good housekeeping practices. Work areas should be kept clean and tidy at all times.

iv. Be alert and proceed with caution at all times in the laboratory. Notify the instructor immediately of any unsafe conditions you observe.

5.0 Procedures5.1 Determination of friction coefficient

i. Set the plane horizontal. This can be achieved with of a spirit level.

ii. Place the sliding objects on plane and hook them to the empty weight hanger by means of a rope.

iii. Add weights to the hanger until the sliding objects tend to move.

iv. Note down the material combination, weight and rope force.

v. Repeat the experiments with other material combination.

5.2 Force on the incline plane

i. Set the plane at 30 inclination angle.

ii. Add weight of 4N to the weights hanger.

iii. Place sliding object with aluminum side on the plane and hook it with the weight hanger by means of a rope.

iv. Add weight to the hanger until the sliding objects tend to move.

v. Note down the materials combination, weight and rope tension.

vi. Decrease the weight gradually until the sliding object tends to move downward the weights.

6.0 Result/Data6.1 Determination of the friction coefficient for different materials.

The experiment has given the following result:

Measurement of the coefficient of friction.

Angle of the plane is 0 , weight (W) = 10N ,

Material combination Rope force, S (N)Friction coefficient (

steel

brass

polypropylene

aluminum

6.2 Force on the incline plane

The experiment has given the following result:

Rope force on incline plane , = 30

Steel, , weight (W) = 10N

Direction of motion Measured rope (N) Calculated rope force (N)

Upward

Downward

Rope force on incline plane , = 30

Brass, , weight (W) = 10N

Direction of motion Measured rope (N) Calculated rope force (N)

Upward

Downward

Rope force on incline plane , = 30

Polypropylene, , weight (W) = 10N

Direction of motion Measured rope (N) Calculated rope force (N)

Upward

Downward

Rope force on incline plane , = 30

Aluminum, , weight (W) = 10N

Direction of motion Measured rope (N) Calculated rope force (N)

Upward

Downward

7.0 Discussion

i. Analyze the result with the theory.ii. The factor that influence the experimental result.

8.0 Conclusion and RecommendationYour conclusion should be related to your practical and theoretical understanding on the related topic.9.0 ReferencesJoseph Edward Shigley and John Joseph Uicker, Jr. (1995), Theory of Machines and Mechanisms. Second Edition, McGraw-Hill International Editions.Friction force, F

Reaction force, QUOTE

Mg

Movement direction

External force, P

Figure 1.1

Friction force, F

Mg

Movement direction

External force, P

Mg sin

Mg cos

Reaction force, QUOTE

Friction force, F

Mg

Movement direction

External force, P

Mg sin

Mg cos

Reaction force, QUOTE

Friction force, F

Mg

Movement direction

External force, P

Mg sin

Mg cos

Reaction force, QUOTE

Figure 1.2

Version : 021211_0.0 _Effective:Jun 2012