What is the car's stopping distance if the speed is doubled?

Question

A car traveling at 10 m/s hits the brakes and comes to a stop in 12 m. What is the car's stopping distance if the speed is doubled?

Answer 1

By the Work-Energy Theorem, the work done in stopping the car = change in kinetic energy.

w = F x d = 0.5 mv²            d = 0.5 mv² / F

 

W = F x D = 0.5 mV²           D = 0.5 mV² / F

 

Since V = 2v                        D = 0.5 m(2v)²/ F

                                  

                                           D = 4 (0.5 mv²/ F) = 4d

 

Hence, the stopping distance is quadrupled if the speed is doubled.

Answer: 48 m

Answer 2

four times the braking distance if the speed doubled

 

I found this on this website below.

 

http://www.bbc.co.uk/schools/gcsebitesize/science/add_ocr_gateway/forces/motionrev3.shtml

 

http://www.gcsescience.com/pfm29.htm