A stone falls freely such that the distance covered by it in the last second of its motion is equal to the distance covered by it in the first 5 seconds. It remained in air for :-

Answer

B, C, D

Explanation

Range `=(u^(2)sin 2theta)/(g)rArr 480=4900/980xxsin 2theta`
`(90-theta)` projection angle has sme range. ltbtgt time of flight :
`T_(1)=(2u sin theta)/(g), T_(2)=(2u sin(90-theta))/(g)`