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Posted 2004-02-24, 09:42 PM
in reply to Demosthenes's post starting "11. A: Approximately 1.54 seconds
11...."
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A) The chand has 24 feet to fall before hitting you.
Since I do not know where the naught key is, I will use @ instead.
X = X@ + V@t + 1/2(a)t^2
X@ = 24
V@ = 0
a = -9.81 m/s^2 = -32.2 ft/s^2
So, when X = 0,
0 = 24 - 1/2 (32.2) (t^2)
t^2 = 48/32.2 = 1.4907
t = sqrt(1.4907) = 1.22 seconds (plus or minus, but since time is only positive...)
1.22 seconds.
B)
V = V@ + at
V@ = 0 So,
V = at
t = 1.22 from A)
V@ = (-32.2) (1.22) = -39.3 feet/second
39.3 feet/second downward
C)
There's a much easier way to do this, but I can't remember the equation... Anyhow...
X = X@ + V@t + 1/2 (a) t^2
X@ = 25 feet
V@ = 0
X = 0
0 = 25 - 1/2 (32.2) t^2
t^2 = 50/32.2 = 1.55
t = sqrt(1.55) = 1.25 seconds
V = V@ + at
V@ = 0
V = (-32.2) (1.25) = -40.25 feet/second
Since speed is a scalar and has no direction, the difference is |-40.25 - -39.3| = .95
0.95 feet/second greater
With all physics, regardless of whether or not the problem was worked correctly, there is a 20% chance that those answers are incorrect. If I cared more, I would check the answers, but... I don't care. I only do this because I enjoy it. *sigh*
Btw, this is physics, not math.
D3V said:
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What is it they say about silence being golden?
Last edited by Medieval Bob; 2004-02-24 at 09:45 PM.
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