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Which of the following statements are correct ?
(A) Centre of mass of a body always coincides with the centre of gravity of the body
(B) Centre of mass of a body is the point at which the total gravitational torque on the body is zero
(C) A couple on a body produce both translational and rotation motion in a body
(D) Mechanical advantage greater than one means that small effort can be used to lift a large load
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- (A) and (B)
- (B) and (C)
- (C) and (D)
- (B) and (D)
Correct Option: D
Centre of mass may or may not coincide with centre of gravity. Net torque of gravitational pull is zero about centre of mass.
τg = ∑τi = ∑ri × mig = 0
Mechanical advantage , M. A.= Load/Effort
If M.A. > 1 ⇒ Load > Effort
