Question

A balloon starts rising from the ground with an acceleration of 1.25 $m/s^2$. After 8 seconds, a stone is released from the balloon. Mark the incorrect option

• A. Will move up for 1 sec after being released
• B. Will cover 5m in its upward motion (after being released)
• C. Reach the ground in 4 second
• D. Cover a distance of 40 m in reaching the ground

Answer 1

The correct option is D

Cover a distance of 40 m in reaching the ground

Height of balloon when stone is released
$H=\frac{1}{2}a{t}^2$
$=\frac{1}{2}\times 1.25\times (8{)}^2$
$=40m$
Velocity(upward) at this point
V = 1.25$\times$8 = 10m/s
Hence when the stone is released it has velocity of 10m/s upwards so it will move for time t. We know
v-u = at
in this case u = 10m/s and v = 0
so we get t = 1sec
it will cover some distance upward in this time