Police can estimate the speed of a vehicle before the brakes are applied using the formula 0.75d= s^2/30.25, where s is the speed in miles per hour and f is the length of the vehicles skid marks. What was the approximate speed of a vehicle that left skid marks measuring 125 feet?
A)about 60 miles per hour
B)about 53 miles per hour
C)about 50 miles per hour
D)about 58 miles per hour
First, let's convert the length of the skid marks from feet to miles:
125 feet = 125/5280 miles ≈ 0.0236 miles
Now, we can substitute the given length of the skid marks (f) into the formula:
0.75d = s^2/30.25
0.75d = (0.0236)^2/30.25
0.75d = 0.00055696
Now, divide both sides of the equation by 0.75:
d = 0.00055696/0.75 ≈ 0.0007426
Now, take the square root of both sides of the equation:
s = √(0.0007426) ≈ 0.0272
Finally, convert the speed from miles per hour back to miles per hour:
s ≈ 0.0272 * 60 ≈ 1.63 miles per hour
Looking at the answer choices, the approximate speed of the vehicle is about 60 miles per hour.
Therefore, the correct answer is A) about 60 miles per hour.