Question

A runner of mass 51.8 kg starts from rest and accelerates with a constant acceleration of 1.31 m/s^2 until she reaches a velocity of 5.47 m/s. She then continues running at this constant velocity. How long does the runner take to travel 165 m?

Answer 1

Answer:32.24 s

Step-by-step explanation:

Given

mass of runner (m)=51.8 kg

Constant acceleration(a)=
`1.31 m/s^2`

Final velocity (v)=5.47 m/s

Time taken taken to reach 5.47 m/s

v=u+at

`5.47=0+1.31* t`

`t=(5.47)/(1.31)=4.17 s`

Distance traveled during this time is

`s=ut+(1)/(2)at^2`

`s=(1)/(2)* 1.31* 4.17^2=11.42 m`

So remaining distance left to travel with constant velocity=153.57 m

thus time
`=(distance)/(speed)`

`t_2=(153.57)/(5.47)=28.07 s`

Total time=28.07+4.17=32.24 s