Question

A balloonist is ascending at a velocity of 12 ms^-1 and acceleration 2 ms^-2. A packet is dropped from it when it is at a height of 65 m from the ground, it drops a packet. Time taken by the packet to reach the ground is

• A. 5 s
• B. -5 s
• C. 7 s
• D. 13/5s

Answer 1

Answer: (A)

5 s

Answer 2

Using h = ut + 1/2 gt² we get

- 65 = 12t – 1/2 × 10 × t²

or 5t² – 12t – 65 = 0

Solving t = 5 s or -13/5 s

Time cannot be negative, thus t = 5 s.