A vertically projected body attains the maximum height in 6s. The ratio of kinetic energy at the end of 3rd second to decrease in kinetic energy in the next three seconds is

Let H is Maximum ht. attained in 6 sec                 u=gt=60ms−1 After 3 sec v=u−gt=60−30=30ms−1 KE at  end  of 3rdsdecrease  in KE  in  next  3s=12m(30)212m(30)2=1                 KE after3secDecrease in  KE after  3sec=KE after 3secPE after 3sec                                                                       =   H2H2=1:1