Question

The point at which an applied force produces a linear acceleration but no rotation is:
A) Centre of gravity       
B) Centre of body
C) Weight of body
D) None of these

Answer 1

A)

Answer 2

The answer is A) to the centre of gravity, since the centre of gravity does not always conform to the centre of the body. In such a situation, a force directed to the centre of the body with a displaced centre of gravity will cause the object to rotate about the centre of gravity.

in a more technical sense, the centre of gravity is the point about which an object will rotate upon applying a force to the body some distance away (known as the moment of the force or torque ). Since the moment of the force creates the rotation, and is given by the force x distance from the centre of gravity, then if the distance is zero (i.e. directed at the centre of gravity), no moment or torque is produced, and hence no rotation happens.

Answer 3

That was a great explanation. Thanks JonnyMcA :)