Question

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

Answer 1

The runner's acceleration was
`1\ m/s^2`

Step-by-step explanation:

Constant Acceleration Motion

It's a type of motion in which the velocity of an object changes by an equal amount in every equal period of time.

Being a the constant acceleration, vo the initial speed, vf the final speed, and t the time, the following relation applies:

`v_f=v_o+at`

Solving for a:

`\displaystyle a=(v_f-v_o)/(t)`

The runner speeds up from vo=5 m/s to vf=9 m/s in t=4 seconds, thus:

`\displaystyle a=(9-5)/(4)`

`\displaystyle a=(4)/(4)=1`

The runner's acceleration was
`1\ m/s^2`