Astudent throws a set of keys vertically upward to his fraternity brother, who is in a window 3.95 m above. the brother's outstretched hand catches the keys 1.75 s later. (take upward as the positive direction. indicate the direction with the sign of your answer.) (a) with what initial velocity were the keys thrown?

Vo = 10.84 m/s

Explanation:

1) Data:

d = 3.95m

t = 1.75s

g = 9.81 m/s²

Vo = ?

2) Formula

Vertical motion ⇒ d = Vo×t - g×t² / 2

3) Solution

Clearing Vo, you get:

Vo = [ d + gt² / 2] / t

⇒ Vo = [ 3.95m + 9.81 m/s² (1.75s)² / 2 ] / 1.75s = [3.95m + 15.02m] / 1.75s

Vo = 18.97 m / 1.75s = 10.84 m/s

connect the batteries in series and hope

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