Two bodies A and B have masses 20 kg and 5 kg respectively. Each one is acted upon by a force of 4 kg wt. If they acquire the same kinetic energy in times `t_A` and `t_B`, then the ratio `t_A/t_B` is

Options

A. `1//2`
B. 2
C. `2//5`
D. `5//6`

Answer

B

Explanation

Given `1/2 m_A v_A^2 = 1/2 =m_Bv_B^2`
According to impulse Momentum theorem
`(FDeltat_A)/(FDeltat_B)=(m_ADeltav_A)/(m_BDeltav_B)=20/5 xx1/2 =2`
`implies (Deltat_A)/(Deltat_B)=2/1 = 2:1 `