Force: It is an external agency either push or pull which changes or tends to change the state of rest or of uniform motion of a body, upon which it acts.
Effects of force : i) It may change the state of a body i.e. the state of rest or state of motion. ii) It may accelerate or retard the motion of a body. iii) It may turn or rotate the body on which it acts. iv) It may deform the body on which it acts.