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Home Engineering Mechanics Electrical Machines To verify the law of parallelogram of forces by universal force table apparatus.
Electrical Machines Lab Experiments

To verify the law of parallelogram of forces by universal force table apparatus.



Aim

To verify the law of parallelogram of forces by universal force table apparatus.

Theory:

This law states that “if a number of coplanar, concurrent forces Is represented in magnitude and direction by the sides of a polygon taken in order then their resultants represented in magnitude and direction by the closing side of the polygon but in opposite order”.

Apparatus Used:

apparatus
  1. Universal force table
  2. Strings
  3. Weights
  4. Hangers
  5. Drawing Sheets

Procedure:

  1. Draw the thread over the pulley and connect the hangers at one end of string whose other end is connected to the circular ring.
  2. Add suitable weights in each hanger till the ring is in centre and apply load in the thread in such a way that all the forces are in equilibrium.
  3. Mark the position of thread with the help of mirror on paper and join all the points.
  4. Measure the angles between the strings and read the values of the corresponding weights
  5. Draw the vector diagram and calculate the percentage error.
  6. Repeat the experiment for minimum five sets.

Observations and Calculations:

S.no Experimental Angles/α1/α2/α3/α4/α5 Experimental weights/F1/F2/F3/F4/F5 Graphical/F5'/α5' Percentage error/F5-F5'/F5 x 100/ α5- α5'/α5' x 100
1
2
3
4
5

Result:

  1. Law of Polygon of Forces- ________________(Verified /Not verified)
  2. For ____ sets of observations, the observed percentage error is____________________

Precautions:

  1. Pulleys should be smooth.
  2. Place the weights gently
  3. Plotting should he done carefully
  4. Clean the apparatus carefully.
  5. The ring should be at centre for equilibrium position./li>

Viva Questions:

Q.-1 Define free body diagram?

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Q.-2.What is equilibrant?

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Q.-3.What are the analytical and graphical conditions of equilibrium of a ringid body?

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Q.-4. What are the difference between force polygon and funicular polygon?

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Q.-5. Define the term Resultant.

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Q.-6. Differentiate between Resultant and Equilibrant

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