Police can estimate the speed a car had been travelling using the length of the skid marks. One formula used for this purpose is v=-7+8.2 $\sqrt{d}$√ d , where v is the speed, in kilometres per hour, and d is the length of the skid marks, in metres.
c.) What would have been the speed of a car, to the nearest kilometre per hour, that would have resulted in 150m skid marks?
6 years ago
Answered By Leonardo F
We basically need to apply the equation provided:
$v=-7+8.2\sqrt{d}$v=−7+8.2√d
Since the skid marks distance is 150 m:
$d=150m$d=150m
$v=-7+8.2\sqrt{150}$v=−7+8.2√150
If we simplify the square root:
$\sqrt{150}=5\sqrt{6}$√150=5√6
Hence:
$v=-7+8.2\left(5\sqrt{6}\right)$v=−7+8.2(5√6)
v=93 km/h
6 years ago
Answered By Jinseo L
You have the equation: $v=-7+8.2\sqrt{d}$v=−7+8.2√d where v is speed(km/h) and d is distance(m). You are given the distance, so plug that into the equation and solve for v.
1. $v=-7+8.2\sqrt{150}$v=−7+8.2√150
2. $v=-7+100.429$v=−7+100.429
3. $v=93.429$v=93.429
Note* For this question you must use the units provided by the question...
6 years ago
Answered By Eric C
The speed of a car in kilometers per hour (km/h) can be determined from the length of the skid marks using the formula presented in the background information.
ie. v = -7 + 8.2 $\sqrt{d}$√d , where v is the speed of the car in km/h, and d is the length of the skid mark in meters (m), which is given.
The question asks to determine the speed of a car that produced a skid mark of 150m. Therefore, we are given the information that d= 150m. From this we can solve.
v = $-7+8.2\sqrt{d}=-7+8.2\sqrt{150}$−7+8.2√d=−7+8.2√150
v = 93.4 km/h
6 years ago
Answered By Sagar G
Given formula v = -7 + 8.2 $\sqrt{d}$√d where d is given as 150
So v= -7 + 8.2 $\sqrt{150}$√150
v+ 93.4 km/h