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 rotational motion in a body.(d) Mechanical advantage greater than one means that small effort can be used to lift a large load.
- A(b) and (d)
- B(a) and (b)
- C(b) and (c)
- D(c) and (d)
Solution & Step-by-step Explanation
- (a) is wrong: COG and COM only coincide in uniform gravitational fields.(b) is correct: Total gravitational torque is zero about the center of mass.(c) is wrong: A couple only produces pure rotational motion (net force is zero).(d) is correct: . If , then .