Here the motion is described
in successive intervals of time.

In this type of problem
the distance travelled is given for two successive intervals of time.

The method of solution is:*
Treat both sections from the starting point for the first interval, not
from their individual starting points.*

An example will illustrate this point

**1993 Leaving Certificate
Higher Level.**

A particle moving in a straight
line travels 30m,54m and 51m in successive intervals of 4,3,2s. Verify
that the particle is moving with uniform acceleration.

Stage ab:

Stage ac:

Now solve two simultaneous
equations in two unknowns, u and f, to give:

Stage ad: