Determine the acceleration of the body if in 5 seconds the body has changed its speed from 30m / s to -15m / s.

Given:

V1 = 30 meters per second – initial speed of the body;

V2 = -15 meters per second – the final speed of the body;

t = 5 seconds – the period of time during which the body changed its speed from V1 to V2.

It is required to determine a (m / s2) – the acceleration of the body.

To determine the acceleration of a body, you need to use the following formula:

a = dV / t = (V2 – V1) / t = (-15 – 30) / 5 = -45 / 5 = -9 meters per second squared.

The minus sign means that the acceleration is directed towards the negative side of the coordinate system (the direction is opposite to the direction of the initial velocity).

Answer: the acceleration of the body is -9 m / s2.