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I keep on getting 3.2s but i don't think thats correct

 

When solving this problem, take down to be negative and right to be positive. A ball is thrown horizontally from the top of a building 51.2 m high. The ball strikes the ground at a point 111 m from the base of the building. The acceleration of gravity is 9.8 m/s 2 . Find the time the ball is in motion. Answer in units of s.

 Jan 28, 2021
 #1
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By the quadratic formula, the answer is 3.4 seconds.

 Jan 28, 2021
 #2
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The ball will hit the ground in   t   seconds

 

-51.2 = y+ vo t   -  1/2 a t^2

-51.2 =  0  +   0   - 1/2 (9.8) t^2             

t = 3.232 seconds

 Jan 28, 2021
 #3
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....as an aside...and you may be asked this in the rest of your exercise

      the ball travels 111 m horizontally in 3.232 seconds

                   111/3.232 =  34.34 m/s inital horizontal velocity

Guest Jan 28, 2021

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