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A ball initially at rest is dropped from an unknown height. Right before the ball hits the ground, it reaches a velocity of 30 m/s. Assuming air resistance is negligible, calculate the initial height of the object.
A.
15 m
B.
30 m
C.
45 m
D.
75 m

Respuesta :

Answer:

45m

Explanation

Using third equation of motion which's vf^2 - vi^2 = 2gh in case of vertical motion so ,

step 1 : (30)^2 - (0)^2 =  2(10) h

step 2 : 900 = (20)h

step 3 : 900/20 = h

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