Determination of weight of an object using the principle of moments

DETERMINATION OF WEIGHT OF AN OBJECT USING THE PRINCIPLE OF MOMENTS

Aim:

To determine the weight of an object using the principle of moments

Apparatus required:

A metre scale, a knife edge, slotted weights, thread

Procedure:

i.                     A metre scale is supported at its centre of gravity by a knife edge or suspended by using a thread tied to its centre so that the scale is in the horizontal position. Ensure that the scale is in equilibrium position.

ii.                     A known weight W₂ and an unknown weight W₁ are suspended from to either side of the the scale using the weight hangers.

iii.                     Fix the position of one weight hanger and adjust the position of the second weight hanger such that the scale is in equilibrium.

iv.                     Measure the distance d₁ and d₂ of the two weight hangers from the centre of the scale accurately.

v.                     The experiment is repeated for different positions of the unknown weight. Measure the distances. The reading are tabulated as follows:

Observation:

Calculations:

Moment of a force can be calculated using the formula

Moment of the force = Force x distance

Clock wise moment by unknown weight = W₁ × d₁

Anticlockwise moment by known weight = W₂ × d₂

W₁ × d₁= W₂ × d₂

w1 w2

Unknown weight = W1= [ W₂ × d₂ ] /d₁

Result:

Using the principle of moments, the weight of the unknown body W₁ = ……. Kg Wt.