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Here is a formula used to work out the speed v mph of a car making an emergency stop
V=squareroot 21d
D feet is the length of the mark the cars tyres make on the road when making an emergency stop
A car makes an emergency stop the cars tyres make a mark 90 feet long work out the speed of the car give your answer correct to the nearest whole number

Respuesta :

So D= 90...

V = squareroot 21(90)
21(90) = 1890
squareroot 1890 = 43.47
V = 43.47 ... to the nearest whole number is 43mph