Question

A ball dropped from a balloon reaches the ground in 10 sec find the height of yhe balloon if it was at rest in the air amd it was rising up with a speed of 20 m/s when the ball was dropped

Answer 1

Answer:-

h = 500 m

H = 700 m

Given:-

u = 0 m/s

t = 10 s

g = 10 m/s²

Speed of balloon = 20 m /s

To find :-

It's height when it is rest in air and when rising up with speed of 20 m/s.

Solution:-

Case :- 1

when balloon is at rest,

u = 0 m/s

g = 10 m/s²

t = 10 s

By using 2nd equation of motion.

Height covered by ball is given by :-

$h = ut + \dfrac{1}{2} gt^2$

$h = 0 \times 10 + \dfrac{1}{2}\times 10 \times (10)^2$

$h = \dfrac{1}{2}\times 10 \times100$

$h = 5 \times 100$

$h = 500 m$

hence, when balloon is at rest it's height will be 500 m.

Case:- 2

When, balloon rises with a speed of 20 m/s

v = 20 m/s

t = 10 s

Then,height covered by balloon is:-

$h" = vt$

$h" = 20 \times 10$

$h" = 200 m$

hence,

When ballon rises with a speed of 20 m/s it's height will be :-

H = h + h"

H = 500 + 200

H = 700 m