Force changes the shape or position of an object. When kicking a ball, force is applied so giving speed to the ball and also changes its position. Force is a vector quantity having both magnitude and direction. Force will cause motion. The unit of force is Newton (N) or kgm/s². (Draunidalo, j., Koroi, I., & Dianimoto, N., 2015, p.25).
Newton’s second law states that “the relationship between the resultant force, F, acting on an object; the mass, m, of the object; and the acceleration, a, of an object is:
F = ma
Where F is measured in N, m in kg and a in ms-2.
Torque or Moment refers to the turning effect of force and is measured by the product of the force and the perpendicular distance of the force from the turning point.
Torque or Moment = Force x perpendicular distance
Figure 1: Example of moment on a simple Beam
Couple occurs where two equal and oppositely directed forces act at a distance apart. A couple causes rotation only and the moment of the couple about any point is Force x distance that is one of the force by the perpendicular distance between the two force.
Figure 2: Example of couple