Question

a lorry starts from rest and moves eith a constant acceleration of 8ms-2 . compute its velocity and the distance travelled after 4s has ellapsed

Answer 1

The distance travelled by a body with constant acceleration (and zero initial speed) is:

$$d = \dfrac{at^2}{2}$$

where $a = 8m/s^2$ is its acceleration, $t = 4s$ is ellapsed time. Thus, obtain:

$$d = \dfrac{at^2}{2} = \dfrac{8\cdot 4^2}{2} = 64m$$

The velocity is:

$$v = at = 8m/s^2\cdot 4s = 32 m/s$$

Answer. 32 m/s, 64m.