Question 752500
All the scene of a accident police can estimate the speed a car had been travelling by the length of the skid mark . 
One formula used for this purpose is V = -7 + 8.2 √(d) where v is the speed in the kilometers per hour and d is the length of the skid mark in metres. 
a) Solve the formula for d
8.2*sqrt(d) = V+7
sqrt(d) = (V+7)/8.2
d = [(V+7)/8.2]^2
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b) how long would the skid mark of the car breaking from 60 kilometre per hour?
d = [(60+7)/8.2]^2 = 66.76 meters
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c) What was the speed of the car if the length of the skid mark is 50 metres?
V = -7 + 8.2sqrt(d)
V = -7 + 8.2*sqrt(50)
V = -7+ 57.98
Velocity = 50.98 km/hr
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Cheers,
Stan H.
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