Question

a balloon is at a height of 81 m and is asending upward with the velocity of 12m/s . a body of 2 kg weight is dropped from it. if g =10m/s² the body will reach the the surface of earth in

1. 1.5 sec
2. 4.025 sec
3. 5.4 sec
4. 6.75 sec
please give me correct explanation as soon as possible . ​

Answer 1

Answer:

Correct option is

C

5.4s

Using the equation : h=ut+21gt2

⇒81=−12t+21×10×t2⇒t=5.4sec