Physics Practicals - For Class IX (Science Group) PRACTICAL 03: To verify the Principle of Moment by using a meter rod balanced on a wedge.

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PRACTICAL 03:

To verify the Principle of Moment by using a meter rod balanced on a wedge.

APPARATUS:

• Metallic stand with sharp wedges block
• Uniform meter scale
• Weights
• Thread Or Hooks

THEORY:
Torque or moment of force is the measuring effect of force produced in a body about certain axis.

Torque = Force x Force arm

T = F x d

Its unit is Newton-meter. Anti clock wise torque is positive and clockwise torque is negative.

PRINCIPLE: (1 MARK)
If algebraic sum of all the torque is zero the body is said to be is equilibrium.

MATHEMATICALLY:
Anti clock wise Torque = Clockwise Torque

METHOD: (2 MARK)

• Pivot the meter rod in horizontal position from its mid point.
• With the help of thread loops or hooks suspend two different weights W₁ and W₂ on the right hand side, and W₃ and W₄ on the left hand side of the fulcrum.
• Adjust these weights so that the meter rod is again horizontal.
• Note down the value of W₁, W₂, W₃ and W₄, and their corresponding moment arms d₁, d₂, d₃ and d₄.
• Take these sets of observation by changing weight and their position.
• For each set of observation calculate clockwise and anticlockwise torque.

OBSERVATIONS:

OBS	CLOCKWISE MOMENTS (TORQUES)				ANTICLOCKWISE MOMENTS (TORQUES)
	W1 (gm-wt)	d1 (gm-wt)	W2 (gm-wt)	d2 (gm-wt)	W3 (gm-wt)	d3 (gm-wt)	W4 (gm-wt)	d4 (gm-wt)
1
2
3

CALCULATIONS:

Sum of clock Torque = Sum of anti clock Torque

W₁ X d₁ + W₂ x d₂ = W₃ X d₃ + W₄ x d₄

1. ---------- + ---------- = ---------- + ----------

  ---------- + ---------- = ---------- + ----------

---------- gm wt - cm

2. ---------- + ---------- = ---------- + ----------

  ---------- + ---------- = ---------- + ----------

---------- gm wt - cm

3. ---------- + ---------- = ---------- + ----------

  ---------- + ---------- = ---------- + ----------

---------- gm wt - cm

RESULT:
Since in equilibrium position of meter rod, sum of clockwise moments is equal to the sum of anti clockwise moments therefore principle of moment is verified.

FIGURE: (1.5 MARKS)

MOMENT APPARATUS

PRECAUTIONS:

• Weights must be standard.
• Loops of thread must be small and equal in size.
• In equilibrium position scale must be horizontal.

Special Thanks to Sir Sajjad Akber Chandio