The body speed changed from 20 to 5 m / s in 15 s. With what acceleration did the body move?

V0 = 20 m / s – initial velocity of the body;

V1 = 5 m / s – body speed at the end of the time interval t;

t = 15 s – the time during which the speed changed from V0 to V1.

It is required to find a – the acceleration of the body.

a = (V1 – V0) / t = (5 – 20) / 15 = -15 / 15 = -1 m / s ^ 2.

Answer: the acceleration is -1 m / s ^ 2 (a negative sign indicates that the body was decelerating).