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A boy throws a stone horizontally from the top of a cliff of height h toward the

ID: 1539258 • Letter: A

Question

A boy throws a stone horizontally from the top of a cliff of height h toward the ocean below. The stone strikes the ocean at distance d from the base of the cliff. In terms of h, d, and g, find expressions for the following.

(a) the time t at which the stone lands in the ocean
t =  

(b) the initial speed of the stone
vxi =  

(c) the speed of the stone immediately before it reaches the ocean
vf =  

(d) the direction of the stone's velocity immediately before it reaches the ocean
f =  below the horizontal

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Explanation / Answer


apply from kinemtice equations of a projectile motion

h = ut + 0.5 gt^2

gt^2 = h

t = sqrt(2h/g)

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b) initial speed vxi = distance /time

Vxi =d * sqrt(g/(2h))

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c) Vertical final speed vy = sqrt(2gh)


v = sqrt(Vxi^2 + Vy^2)

v = sqrt(d^2g/(2h) + 2gh]


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part D:

d) tan-1(vy/vxi)

theta = tan-1(2h/d)