ABSTRACT
This chapter discusses the motion in a circle. Velocity is a vector quantity and has both size and direction. Acceleration is the rate of change of velocity. Thus, there will be an acceleration if a velocity changes either as a result of equal distances in the same straight line not being covered in equal times or, if equal distances are being covered they are not in the same straight line, that is there is a change in direction. This is what happens with circular motion where we can have equal distances round the circumference of the circular path covered in equal times that is constant speed but the velocity is changing because the direction is continually changing and so there is acceleration. The centripetal force necessary for the acceleration is: According to Newton's third law, to every action there is an opposite and equal reaction.
