Verify the Second Condition of Equilibrium.

Experiment to verify the second condition of equilibrium using a meter rod and suspended weights by balancing clockwise and anticlockwise torques.

1. Apparatus

   Meter rod, sharp wedge, three weights (W₁, W₂, W₃), and a stand.

    

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   Procedure

   Firstly, take a meter rod and find its center of gravity (G) by balancing it carefully on a sharp wedge.
   Next, suspend three weights — W₁ on the right side and W₂ and W₃ on the left side of the meter rod.
   Afterward, balance the meter rod on the wedge again and record the positions of all the suspended weights.
   Meanwhile, ensure the rod remains perfectly horizontal for accurate readings.
   Then, apply the second condition of equilibrium, which states that:

   $$\text{Sum of anticlockwise torques}=\text{Sum of clockwise torques}$$

   Therefore, the relationship can be written as:

   Tanticlockwise=TclockwiseT_{\text{anticlockwise}} = T_{\text{clockwise}}Tanticlockwise​=Tclockwise​

   Finally, determine the center of gravity (G) of the meter rod using this condition.

NO.of.Obs.	Weight suspended			Position of				Distance
	W1	W2	W3	W1	W2	W3	AG		BG	CG
				A	B	C
	N	N	N	m	m	m	m		m	m

No of  Obs.	Anticlockwise Torque		Clockwise Torque	⅀t =0
	T2=wBG	T2=WCG	T=-w1AG	⅀t =t1+t2+t3=0
	N.m	N.m	N.m	N.m
1 2 3

Calculation

The second condition of equilibrium requires:

∑T=0⇒T1+T2+T3=0\sum T = 0 \Rightarrow T₁ + T₂ + T₃ = 0∑T=0⇒T1​+T2​+T3​=0

If the above condition is satisfied, equilibrium is verified.
Moreover, this proves that the opposing torques balance each other perfectly, keeping the system stable.

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Precautions

1. The meter rod must be suspended edgewise to reduce measurement errors.

2. Both ends of the rod should be at equal height from the ground to ensure balance.

3. Take readings only when the rod becomes completely stationary.

4. Handle weights carefully; sudden movement may shift the center of gravity.

5. Repeat the experiment for accuracy and compare your results.

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Viva Voce

Q1. What is the center of gravity?
Ans: It is the point where the entire weight of a body appears to act.

Q2. Define torque.
Ans: Torque is the turning effect of a force, equal to the product of the force and its moment arm.

Q3. What is a moment arm?
Ans: It is the perpendicular distance between the line of action of the force and the axis of rotation.

Q4. Define the first condition for equilibrium.
Ans: The sum of all external forces acting on a body must be zero.

Q5. Define the second condition for equilibrium.
Ans: The sum of all external torques acting on a body must also be zero.