Question

a boy releases his balloon, which slowly rises into the sky. if the balloon has a diameter of 20.0 cm when the child releases it, what is its diameter at a height of a) 1,000 m, b) 2,000 m, and c) at 5,000 m? assume that the balloon is very flexible and that you can neglect the surface tension

Answer 1

Answer:



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Class 11

>>Physics

>>Motion in a Straight Line

>>Problems Based on Free Fall

>>A balloon is going upwards ...

Question



A balloon  is  going upwards with  velocity 12 m/s. It releases a packet when it  is a height of 65 m  from the ground.  How much time will the packet take to reach the ground if g = 10  m/s2  

A

5 second

Correct Answer

B

6 second

C

7 second

D

8 second

Medium

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Solution



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Correct option is

A

5 second

Given,

Take upward direction as -ve and downward direction as +ve.

u=−12m/s

h=65m

g=10m/s2

v=0m/s

From 2nd equation of motion,

h=ut+21gt2

65=−12t+21×10t2

65=−12t+5t2

5t2−12t−65=0

5t(t−5)+13(t−5)=0

t−5=0,5t+13=0

t=−513,5

Time taken to reach the ground is 5sec.