The energy required to accelerate a car from 10 m/s to 20 m / s is how many times the energy required to accelerate the car from rest to 10 m /s

Options

A. Equal
B. 4 times
C. 2 times
D. 3 times

Answer

D

Explanation

Kinetic energy for first condition
`= (1)/(2)m ( v_2^(2) - v_1^(2)) =(1)/(2) m ( 20 ^(2) - 10 ^(2)) = 150 mJ`
K.E. for second condition `= (1)/(2) m ( 10 ^(2) - 0 ^(2)) = 50 mJ ` ` therefore ((KE.)I)/( (K.E.) II) = (150 m)/( 50m ) = 3 `