Question

A balloon going upwards with a velocity of 12m/s is at ht.65 m from earth at any instant.At this instant a packet drops from it.how much time will packet take in reaching earth?

Answer 1

When the packet is released from the balloon , it moves up with the same speed as that of the balloon.

here,

h = - 65m ( -ive sign is b'coz the packet is moving downwards)

u = 12 m/s

a = g = --10 m/s ( taking the value of g as 10 m/s is convenient for this numerical)

Using, h = ut + 1/2 a t2

-65 = 12t - 1/2 *10t2

-65 = 12t - 5t2

5t2 - 12t - 65 = 0

5t2 - 25t + 13t - 65 = 0

5t ( t - 5 ) + 13( t - 5) = 0

( t - 5)(5t + 13) = 0

t =5 or t = -13/5

Since time can never be negative, the packet will take 5 sec. to reach the ground.