Question

A balloon starts rising from the ground with an acceleration of 1.25 m/s² after 8s, a stone is released from the balloon. The stone will ($g = 10$ m/s²)

• A. Reach the ground in 4 second
• B. Begin to move down after being released
• C. Have a displacement of 50 m
• D. Cover a distance of 40 m in reaching the ground

Answer 1

Answer: (C)

Have a displacement of 50 m

Answer 2

When the stone is released from the balloon. Its height

$h = \frac{1}{2}at^{2} = \frac{1}{2} \times 1.25 \times (8)^{2} = 40\mspace{6mu} m$and velocity

$v = at = 1.25 \times 8 = 10\mspace{6mu} m/s$

Time taken by the stone to reach the ground

$t = \frac{v}{g}\left\lbrack 1 + \sqrt{1 + \frac{2gh}{v^{2}}} \right\rbrack = \frac{10}{10}\left\lbrack 1 + \sqrt{1 + \frac{2 \times 10 \times 40}{(10)^{2}}} \right\rbrack$=4 sec