A balloon going upwards with a velocity 12m/s. It releases a packet when it is at a height of 65m from ground. How much time the packet will take to reach the ground if g=10m/s2.
Correct answer: A. 5
- A. 5
- B. 6
- C. 7
- D. 8
Explanation
As the force (pull of the balloon) acting on the packet is removed, it continues its straight-line motion up to the point where the velocity becomes zero.The time taken by the packet to move to the highest point is calculated by the first equation of motion.vf=vi+at0=12-10×t (negative sign shows the deceleration due to gravity)t=1.2 s, in which a distance S=7.2 m is traveled. Calculated the distance using 2nd equation of motion i.e., S=vit+12gt2Now the ball is stationary at the highest point in its journey, it starts falling freely from the height of (7.2 + 65)m. The time for this freefall is t=5s from the 2nd equation of motion.For other options to be right, the packet must have been released from a greater height than 65m.
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