Question

Police can estimate the speed of a vehicle before the brakes are applied using the formula 0.75d = s^2 / 30.25 where is the speed in miles per hour d is the length of the vehicle's skid marks. What was the approximate speed of a vehicle that left a skid mark measuring 160 feet?

1.about 36 miles per hour
2."" 60 ""
3."" 13 ""
4"" 54 ""

Answer 1

The answer would be ≈60mph, hence the answer is B.

Answer 2

So we have the formula to calculate the speed of a vehicle before the breaks were applied using the measure of it's skid marks:
`0.75d= (s^(2) )/(30.25)`
We also know from our problem that the vehicle left a skid mark measuring 160 feet, so
`d=160`. Lets replace that value in our formula to find the speed
`s`:

`(0.75)(160)= (s^(2) )/(30.25)`

`120= (s^(2) )/(30.25)`

`(120)(30.25)=s ^(2)`

`s ^(2) =3630`

`s= √(3630)`

`s=60.25`

We can conclude that the speed of the car before the brakes were applied was about 60 miles per hour.