Answer to Question #206842 in Mechanical Engineering for Rodel

Question #206842

From the top of a building 75m, a bullet is fired at an angle of 45° above the horizontal with an initial velocity of 270 m/s. Find the time until it hits the ground.


1
Expert's answer
2021-06-22T05:10:18-0400

 The initial vertical velocity is downward and the acceleration due to gravity will increase this downward velocity


Vi=270cos450=190.91msecV_i = 270 cos 45^0 = 190.91 \frac{m}{sec}


d=vit+12at2d=v_it+\frac{1}{2}at^2


75=190.91×t+12×9.8×t275 =190.91\times t+\frac{1}{2}\times 9.8\times t^2


Changing to standard quadratic form yields


4.9t2+190.91t75=04.9 t^2 + 190.91t-75 = 0


This equation can be solved with the quadratic Equation:

 

t = 0.39 sec



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Comments

Assignment Expert
23.06.21, 12:56

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Rodel
22.06.21, 21:11

Thank you!

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