Concept:A force is a push or pull measured in newtons that can change the state of motion of a body.
Explanation:I. Force is measured in newtons, so statement I is correct.
II. Newton-metre is the unit of torque or moment of a force, not force itself, so statement II is incorrect.
III. A force can start a motion by making a stationary object move, so statement III is correct.
IV. A force can change the direction of a moving body, so statement IV is correct.
Answer:The correct statements are I, III and IV only.