A truck accelerates from speed v to 2v. Work done during this is

Options

A. three times as the work done in accelerating it form rest to v
B. same as the work done in accelerating it form rest to v
C. four times as the work done in acceleration it from rest to v
D. less than the work done in acclerating it from rest to v

Answer

A

Explanation

Work done to accelerate from 0 to v is, `W_(1)=1/2 mv^(2)`
Work done to accelerate from v to 2v is, `W_(2)=1/2 m (2v)^(2)`
`implies Delta W=W_(2)-W_(1)=1/2 m (2v)^(2) -1/2 mv^(2)=4 W_(1)-W_(1)=3 W_(1)`