A car of mass m moving at a speed v is stopped in a distance x by the friction between the tyres and the road. If the kinetic energy of the car is doubled its stopping distance will be

Options

A. 8x
B. 4x
C. 2x
D. x

Answer

C

Explanation

If a is the deceleration due to the force of friction f, then
`2ax = v^(2)`
or ` (1)/(2) mv^(2) = "max" or KE = fx (because f = ma)`
Thus if KE is doubled , x is also doubled.