Question

If the car had a speed of 2v, it would have skidded a distance of

(A) 0.5d

(B) d

(C) 1.41d

(D) 2d

(E) 4d

Answer 1

Correct option (E) 4 d

Newton’* 2nd law applied to an object sliding to rest gives ΣF = –Ff = –µFN = ma. On a horizontal surface, FN = mg and we have –µmg = ma, or a = –µg. Using this acceleration with vf2 = vi2 + 2ad gives d = vi2/2µg. d is proportional to vi2.