Page 43 - Physics - XI

10. Repeat all the steps from 1 to 9 for diff erent weights for three more observations.

11. Find out the weight of the body by a spring balance and verify your result.

Observations
Scale, let 1 cm = _____ g wt (Y g wt)
Weight of each hanger = _____ g wt

Table for measurement of weight of a given body

S. No. Force = Weight of Length of the sides Unknown Angle COC'
(hanger + slotted weights) weight
P Q OA OB OC X = OC × Y
(g wt) (g wt) (cm) (cm) (cm) (g wt)

1.
2.
3.
4.

Mean value of the unknown weight X = _____ g wt

Calculations
Least count of the spring balance = _____ g wt

Zero error = _____ g wt
Unknown weight of the body by the spring balance = _____ g wt

Corrected weight = W = observed weight + zero correction
= _____ g wt
Diff erence = W – X = _____ g wt

Percentage error = W X 100 = _____%
W
Result
1. The unknown weight of the given body by parallelogram law of vectors is _____ g wt.

2. Percentage error = _____%

Precautions

1. Pulleys should be frictionless.
2. Hangers should not touch the board or the table.

3. The board should be stable and vertical.
4. Weights should be adjusted so that point O lies in the middle of the paper sheet.

5. Points should be marked only when weights are at rest.
6. A proper scale should be chosen so that the parallelogram is formed as large as possible. This would
reduce the error in measurements.

7. An arrow should be marked to show the direction of forces.
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