Question

A car travelling at 30 mph takes 10 m to come to a complete stop. Consider the work done by the brakes when stopping to estimate the distance required to bring the car to a complete stop from 75 mph. What is this distance

Answer 1

The value of the distance S = 62.5 m

Step-by-step explanation:

From third law of motion

`v^(2) = u^(2) + 2 as\\`

v = 0 & u = 30

So 0 =
`30^(2)` + 2 × a × 10

a = - 45
`(m)/(s^(2) )`

When the car speed is 75
`(mi)/(hr)` then in that case

u = 75
`(mi)/(hr)` , v = 0

`v^(2) = u^(2) + 2 as\\`

`75^(2) = - 2 a S`

`S = (75^(2) )/(-2 (-45))`

S = 62.5 m

This is the value of the distance.