Question

A runner covers the last straight stretch of a race in 4 s. During that time, he speeds up from 5 m/s to 9 m/s. What is the runners acceleration in this part of the race?

Answer 1

1m/s^2

Step-by-step explanation:

We can use the Kinematic relationship:

`vf=vi+at`

where:

v f = final velocity;

v i = initial velocity;

a = acceleration;

t = time.

u= 5 m/s

v= 9 m/s

t= 4s

9 = 5 + 4a

4a = 9-5

4a = 4

divide both side by 4

a = 1

a= 1m/s^2

Answer 2

1m/s^2

Step-by-step explanation:

u= 5 m/s

v= 9 m/s

t= 4s

But

a= v-u/t

a= 9-5/4

a= 4/4

a= 1m/s^2