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

Two bodies A and B have masses 20 kg and 5 kg respectively. Each one i

1.	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
Answer» `1/2` `2` `2/5` `5/6` Solution :Here, `m_A = 20 kg, m_B = 5 kg` As force = 40 N `:. a_A = 2 MS^(-2) and a_B = 8 ms^(-2)` ALSO `K_A = K_B` (given) `:. 1/2 m_A (a_A t_A)^2 = 1/2 m_B (a_B t_B)^2` or `1/2 xx 20 xx 4t_A^2 = 1/2 xx 5 xx 64 t_B^2` or `(t_A^2)/(t_B^2) = (1/2 xx 5 xx 64)/(1/2 xx 20 xx 4) = 4/1" or " (t_A)/(t_B) = 2`.