Astone slides in a straight line across a horizontal sheet of ice. i passes a pot a with a velocity of 14 m/s and the point b 2.5s later. assuming the deceleration is uniform and ab=30m, find the deceleration .

The deceleration, a = -1.6 m/s²

Explanation:

Given,

The initial velocity, u = 14 m/s

The time taken by the stone is, t = 2.5 s

The distance between the point, s = 30 m

Using the 2nd equations of motion

                           s = ut + 1/2 at²

∴                         a = 2(s - ut)/t²

Substituting the values

                            a = 2(30 - (14)(2.5))/2.5²

                               = -1.6 m/s²

Hence, the deceleration of the stone, a = -1.6 m/s²

no. dot product   =0 when vecs at right angles