An object is moving east, and its velocity changes from 65 m/s to 25 m/s in 10 seconds. which describes the acceleration?

4 m/s2 in negative acceleration

4 m/s2 in positive acceleration

9 m/s2 in positive acceleration

9 m/s2 in negative acceleration

4 m/s2 in negative acceleration

Explanation:

The acceleration of an object is the ratio of change of its velocity per unit of time. In formula, acceleration is given by

where

v is the final velocity of the object

u is its initial velocity

t is the time taken for the object to change its velocity

In this problem, we have an object with initial velocity u=65 m/s, final velocity v=25 m/s and time taken t=10 s. Therefore, its acceleration is

and the acceleration is negative, because the object is slowing down, so the direction of the acceleration is opposite to the direction of motion of the object. Therefore, the correct answer is

4 m/s2 in negative acceleration