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 An aeroplane flying 490m above ground level at 100m/s, releases a block. After how much time it will hit the ground (g = 9.8 m/s2) -
 

Option: 1

5 sec


Option: 2

10 sec


Option: 3

7.5 sec

 


Option: 4

15 sec


Answers (1)

best_answer

Time of flight

  • Formula

               t= \sqrt{\frac{2h}{g}}

           where   t= time of flight

                        h= Height from which projectile is projected

 

SO,

\\y=U_{y}t-\frac{1}{2}gt^{2}\: \: \: \: \: \: \left \{ U_{y} = 0\right \}\\* \Rightarrow -490=- \frac{1}{2}\times 9.8\times T^{2}\: \: \: \: \: \: \left [ g=9.8m/s^{2} \right ]\\* T^{2}= \frac{490\times 2}{9.8}= 100\\* T=10 Sec

Posted by

manish

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