#24 A dart is thrown horizontally with an initial 10 m/s toward point P, the bul
ID: 1650770 • Letter: #
Question
#24
A dart is thrown horizontally with an initial 10 m/s toward point P, the bull's-eye on a dart board. It hits at point Q on the rim, vertically below P, 0.19 s later. (a) What is the distance PQ? (b) How far away from the dart board is the dart released? In Fig. 4-33, a stone is projected at a cliff of height h with an initial speed of 42.0 m/s directed at angle theta_0 = 60.0 degree above the horizontal. The stone strikes at A, 5.50 s after launching. Find (a) the height h of the cliff, (b) the speed of the stone just before impact at A, and (c) the maximum height H reached above the ground.Explanation / Answer
a) by second equation of motion,
h = u sin 60 degree t - 0.5gt^2
= 42*sin 60 degree *5.5 - 4.9*5.5^2
= 51.83 m answer
b) Vx = 42 cos 60 degree = 21m/s
Vy = 42 sin 60 degree - 9.8*5.5 = -17.527 m/s
speed V = sqrt(21^2+17.527^2)
= 27.35 m/s Answer
c) Maximum height = u^2 sin ^2 60 degree /2g
= (42^2*3/4)/(2*9.8)
= 67.5 m answer
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