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Lab 10 BMM1511 Precision Friction Measurement

lab sheet
Course

Mechanics of Materials (Mec 411)

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Academic year: 2021/2022
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TH200 09_Nur Aisyah
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Lab 10

Precision Friction

Measurement

Lab Location Statics and Dynamics Laboratory

Lab Objectives To identify the influence of frictional force as a function of normal force

1. Theoretical Principles of Frictional Force in Motion.

Generally, if the magnitude of P acts on the block is increased, greater than Fs, the frictional force at the contacting surfaces drops slightly to a smaller value of Fk, called kinetic frictional force. The block will not held in equilibrium (P>Fk) and it will begin to slide with an increasing speed as shown in Figure 1.

Figure 1

Fk = μk N

Here the constant of proportionality μk, is called the coefficient of kinetic friction. Graph in Figure 2 shows the variation of the frictional force F versus the applied load P. Here the frictional force is categorized in three different ways. F is a static-frictional force if equilibrium is maintained; F is a limiting static-frictional force Fs when it reaches a maximum

P

W Motion

Rn

Fk

N

φ

value needed to maintain equilibrium and F is termed a kinetic-frictional force Fk when sliding occurs at the contacting surface. Notice also from the graph that for very large values of P or for high speeds, Fk and μk begin to decrease.

Figure 2

2 Equipment and Components

1 TM 210 Precision Friction Measurement. ( Figure 3 ) 2 Winch drum, diameter 7 mm with towing clip - 1 unit. 3 Friction object, brass / felt FG = 1N ñ 1 unit. 4 Friction plate, glass ñ 1 unit. 5 Friction plate, PVC ñ 1 unit. 6 Six(6) weights, FG = 0 N

Figure 3: Precision Friction Measurement Apparatus

No motion Motion

F= P

P

Fk

Fs

F

45 o

5. Results and Discussion

  1. Plot the graph of friction force versus normal force for all the experiments.
  2. Show a sample calculation for each experiment.
  3. Explain the consequences if the force gauge is not parallel to the surface of the tow- platform while performing the experiment?
  4. Lubricant need to be used to reduce friction during the experiment. Explain with the help of free body diagram a part in the experiment that is not lubricated.
  5. What are the possible factors that contribute to an error reading in this experiment?
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Lab 10 BMM1511 Precision Friction Measurement

Course: Mechanics of Materials (Mec 411)

138 Documents
Students shared 138 documents in this course

University: Universiti Teknologi MARA

Was this document helpful?
Page 36 of 39
BMM1511 Engineering Mechanics Lab 1Vesion 1 ( Nurhani & Lee ) Implementation Date: 01-09-2012
Lab 10
Precision Friction
Measurement
Lab Location
Statics and Dynamics Laboratory
Lab Objectives
To identify the influence of frictional force as a function of normal force
1. Theoretical Principles of Frictional Force in Motion.
Generally, if the magnitude of P acts on the block is increased, greater than F
s
, the frictional
force at the contacting surfaces drops slightly to a smaller value of F
k
, called kinetic frictional
force. The block will not held in equilibrium (P>F
k
) and it will begin to slide with an increasing
speed as shown in Figure 1.
Figure 1
F
k
= μ
k
N
Here the constant of proportionality μk, is called the coefficient of kinetic friction.
Graph in Figure 2 shows the variation of the frictional force F versus the applied load P. Here
the frictional force is categorized in three different ways. F is a static-frictional force if
equilibrium is maintained; F is a limiting static-frictional force F
s
when it reaches a maximum
P
Motion
W
R
n
Fk
N
φ

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