Question

A stone is dropped from a rising ballon at a height of 76m above the ground and reaches the ground in 6sec . What was the velocity of the ballon when the stone was dropped?

Answer 1

Answer:

u=0

s=76m

t=6sec

s=1/2at^2+ut

76=1/2a×36+0×6

76=18a

76/18=a

a=76/18

v=u+at

=0+76/18×6

= 76/3m/s

Answer 2

Answer:

Given:

A stone dropped from rising balloon at a height of 76 m. The stone reached the ground after 6 seconds.

To find:

Velocity of balloon , when stone was dropped.

Concept:

Let's assume that velocity of balloon when stone was released be u . So , we can understand that the same magnitude of velocity will be transmitted to the stone after release and it will be going upwards.

Now gravity shall act on it and bring down the stone towards the ground in 6 seconds. So the Displacement after release of stone is 76 m

Calculation:

$s = ut + \frac{1}{2} a {t}^{2}$

$= > - 76 = u \times (6) - \{ \frac{1}{2} \times (10) \times {(6)}^{2} \}$

$= > 6u = 180 - 76$

$= > 6u = 104$

$= > u = \dfrac{104}{6}$

$= > u \: \approx \: 17.33 \: m {s}^{ - 1}$

So velocity of balloon at the time of release is 17.33 m/s