A balloon starts rising from the ground with acceleration of 1.25m/s sq . After 8s a stone is released from the balloon . How much time will it take to reach the ground ?(g = 10 m/s sq. )
The acceleration of the balloon for rising up,a=1.25m/s2
The velocity of balloon at time,t=8s is 'v'.ï½
In 8s the balloon will rise to,
Now, balloon will drop down with initial velocity,u'=v=10m/s with acceleration,a'=-g=-10m/s2
and cover distance -40m (as it is moving downwards).
We will find,
t=4 or t=-2
Time can not be negative so the required answer is 2 seconds. the stone will hit the ground in 2 seconds.