... The Cause of Acceleration and Newton’s Laws 105 Newton’s Third Law of Motion Forces come in pairs For example, if you lean against a wall with a certain force, the wall reacts and pushes back on ... velocity → v of a particle changes in both direction and magnitude, the acceleration → a can be decomposed to a radial component vector → a r and a tangential component vector → at The tangential ... vector a can be resolved into two component vectors: a tangential → → component vector, a t , and a radial component vector, a r That is: → → → a = ar + at (4.31) at Particle’spath a ar ar a at...