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 produces both translational and rotational motion in a body.(d) Mechanical advantage greater than one means that small effort can be used to lift a large load.
- A(a) and (b)
- B(b) and (c)
- C(c) and (d)
- D(b) and (d)
Solution & Step-by-step Explanation
(a) Incorrect: Coincides only in a uniform gravitational field.(b) Correct: By definition of the center of gravity (which is often taken to be the COM in standard problems).(c) Incorrect: A couple produces only rotational motion (net force is zero).(d) Correct: .