Question

A balloon is rising up with the velocity of 2m/s. When the ballon is at a height of 12m, stone is thrown up with velocity 20m/s towards the ballon. Will the stone hit the ballon and at what height?

Answer 1

When the stone was released from the balloon it had the same velocity and had the same acceleration as that of the balloon.Now when the stone was released it had an upward velocity and the stone would not start to fall unless it's upward velocity becomes zero(if its not logical do comment). The time till which it's upward velocity becomes zero is included in that 11 sec interval.(The velocity would become zero due to the retardation provided by the gravity of earth.)Use Kinematics 1st eqn “V= U +at” put v=0(final velocity) , U=10(initial velocity) , a=9.8/10(as suggested) then find the time.Subtract this time from 11 sec let this be ‘to’Now use the displacement eqn ( S=Ut +1/2at^2)Here simply put t= ‘to’ and U=0 and the displacement of the stone is the height of your stone.