Question

a ballon is going vertically upwards with velocity of 12 m/s . when it is 65 metre above the ground, a stone is gently released from it. the time taken by the songs to reach the ground is

Answer 1

A balloon is going upward with a velocity of 12 m/s. It releases a packet when it is at a height of 65 m from the ground. How much ... It releases a stone which comes down to the ground in 11s. The height

Answer 2

Hi there !
Here's the answer :

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Given,

Balloon with stone is going vertically upward.

Speed of balloon u = 12 m/s

height of the balloon when Stone is released h = 65 m

acceleration due to gravity g =~ 10 m/s

{ g = 9.8 m/s}

We have,

h = -ut + (1/2)gt²

[u = -u as the stone and balloon are moving in opp. direction]

Substitute values

65 = -12t + (1/2)×10×t²

=> 5t² +12 t - 65 = 0

=> 5t² + 25t - 13t - 65 = 0

=> 5t(t + 5) + 13(t - 5) = 0

=> 5t(t-5)+13(t-5) = 0

=> (t-5)(5t-13) = 0

=> t = 5 or t = -13/5

°•° time can't be -ve
=> t = 5 sec


•°• Stone takes 5 sec to reach the ground.

[g is taken as 10 m/s instead of 9.8 m/s to get exact answer]

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