Form a lift moving upwards with a uniform acceleration `a=2 m s^(-2), man throws a ball vertically upwards with a velcoity `v=`12 m s^(-1)` relative to the lift. The ball comes back to the man after a time `t`. Find the value of `t` in seconds.

Answer

B

Explanation

` overset-a_(BL) =overset-a_(B) -overset- a_(L) =-10 ( +2) =-12m//s^(2) `
`overset -a_(BL) =+12m//s ,overset-s_(BL) =overset-u_(BL) t+(1)/(2) overset-a _(BL) t^(2) `
` 0= 12 t +(1)/(2) (-12)t^(2) " "rArr " " t= 2 sec `