Question

A drag racer starts her car from rest and accelerates at 14 meters per second per second for the entire distance of 424 meters. how long does her race take

Answer 1

You can use this 'suvat' equation of linear motion


`s = ut + (1)/(2) a {t}^(2)`
From the question, the racer starts from rest so the initial velocity

`u = 0 {ms}^( - 1)`

The acceleration,


`a= 14 {ms}^( - 2)`

And distance

`s = 424m`

We can substitute this values to find t


`424= (0)t + (1)/(2) (14) {t}^(2)`


`424= 7{t}^(2)`

Dividing by 7, we have


`(424)/(7) = {t}^(2)`


`\sqrt{ (424)/(7) } = t`


`t = 7.8 \: s`

Therefore the race took 7.8 seconds