A dart is thrown horizontally with an initial speed of 6 m/s toward point P, the bull's-eye on a dart board. It hits at point Q on the rim, vertically below P, 0.27 s later. Neglect air resistance.
(a) What is the distance PQ?
___________ m
(b) How far away from the dart board is the dart released?
___________ m
(a) What is the distance PQ?
___________ m
(b) How far away from the dart board is the dart released?
___________ m
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a:
Vertical motion: initial velocity = 0; acceleration = 1g down; time = 0.27 seconds.
s = ut + 1/2 a x t ^2
s = 0 x t x 1/2 x -9.8 x 0.27^2
s = 35.7cm = 0.357m
b:
Horizontal motion: Initial velocity = 6; acceleration = 0; time = 0.27 seconds.
s = ut + 1/2 at^2
s = 6 x 0.27 + 1/2 x 0 x 0.27^2
s = 1.62m.
Vertical motion: initial velocity = 0; acceleration = 1g down; time = 0.27 seconds.
s = ut + 1/2 a x t ^2
s = 0 x t x 1/2 x -9.8 x 0.27^2
s = 35.7cm = 0.357m
b:
Horizontal motion: Initial velocity = 6; acceleration = 0; time = 0.27 seconds.
s = ut + 1/2 at^2
s = 6 x 0.27 + 1/2 x 0 x 0.27^2
s = 1.62m.
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Assuming that point P is vertically even with the point at which the dart is released.
Givens:
Vix = 6m/s
Viy = 0m/s (initial velocity is assumed to be entirely horizontal)
ax = 0 (no air resistance to slow it down)
ay = -9.81m/s^2 (acceleration due to gravity)
t = 0.27s
Vfx = 6m/s
Vfy = ?
dx = ?
dy = ?
a) dy = ?
dy = (Viy)t + (1/2)ay(t^2)
dy = (0m/s)(0.27s) + (1/2)(-9.81m/s^2)(0.27s)^2
dy = 0.358m --> 0.36m (2 significant figures)
b) dx = ?
dx = (Vix)t + (1/2)ax(t^2)
dx = (6m/s)(0.27s) + (1/2)(0m/s)(0.27s)^2
dx = 1.62m --> 1.6m (2 sig figs)
Givens:
Vix = 6m/s
Viy = 0m/s (initial velocity is assumed to be entirely horizontal)
ax = 0 (no air resistance to slow it down)
ay = -9.81m/s^2 (acceleration due to gravity)
t = 0.27s
Vfx = 6m/s
Vfy = ?
dx = ?
dy = ?
a) dy = ?
dy = (Viy)t + (1/2)ay(t^2)
dy = (0m/s)(0.27s) + (1/2)(-9.81m/s^2)(0.27s)^2
dy = 0.358m --> 0.36m (2 significant figures)
b) dx = ?
dx = (Vix)t + (1/2)ax(t^2)
dx = (6m/s)(0.27s) + (1/2)(0m/s)(0.27s)^2
dx = 1.62m --> 1.6m (2 sig figs)