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  GR8677 #7
Problem
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Verbatim question for GR8677 #7
Mechanics}Statics

Straight-forward Newtonian statics:



Divide the two equations above, cancel T's, and get: \par
\tan(\theta)=\frac{F}{mg}=\frac{10}{2*10}=.5. Choice A is right.

See below for user comments and alternate solutions! See below for user comments and alternate solutions!
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Comments
pam d
2011-09-23 19:24:15
free points!NEC
Dodobird
2010-11-04 18:15:41
Any solution must involve horizontal and vertical components of force.
Tangents satisfy this requirement.
Because the box weighs 2 kg already we see gravity, the vertical force, will be larger.
Opposite/Adjacent < 1 means that only A satisfies this requirement.
NEC
signminus
2010-08-01 12:15:58
Not quite. The question asks for the angle, \theta. As in the posted solution, we have
\text{tan}(\theta)=0.5.
To invert this equation, we do
\text{tan}^{-1}(\text{tan}(\theta))=\text{tan}^{-1}(0.5)
\Longrightarrow \theta=\text{tan}^{-1}(0.5),
answer A.
signminus
2010-08-01 12:16:42
Oops, meant that as a reply to rlorek's comment below.
NEC
rlorek
2010-07-30 12:32:55
This was worked out well, but the answers are looking for "arc" functions which are the inverse of normal trig functions.

The inverse of tan(theta)=0.5 is...

arctan(theta)=2.0

Therefor "C" should be the correct answer.
flyboy621
2010-11-09 20:27:00
If tan \theta= .5 then \theta =arctan .5 .
NEC
belle
2009-10-11 13:50:56
This also solvable with simple geometric tactics

tan(theta)=\frac{10}{2g}

using g=10

tan(theta)=.5

NEC
kostas
2007-01-09 12:42:27
I see the answers but I cannot find the questions. Where are they? There was a "jump into the question" buton in the old site that I can't see now
yosun
2007-02-22 19:09:03
I am in the process of typing up the questions. Currently, only GR8677 is available as graphics file displayed next to the official solution. GR9277 questions will be available shortly, and the rest, eventually.
NEC

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