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发表于 26-7-2010 11:49 PM
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回复 319# whyyie
The answer is not that..the tension is not the same |
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发表于 27-7-2010 10:01 PM
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发表于 27-7-2010 10:05 PM
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发表于 27-7-2010 10:18 PM
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本帖最后由 whyyie 于 27-7-2010 10:21 PM 编辑
回复 323# vick5821
Supposing we consider T as the sum of T1 + T2
T sin * = mv^2 / r
T sin 60 = 4(6^2) / (0.8 sin 60)
T = 240N
T/2 = 120N
T1 = T/2 + mg = 120 + 4(9.81) = 159.24 N
T2 = T/2 - mg = 120 - 4(9.81) = 80.76 N |
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发表于 27-7-2010 10:28 PM
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发表于 27-7-2010 10:46 PM
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本帖最后由 whyyie 于 27-7-2010 10:48 PM 编辑
回复 325# vick5821
哪里不明白? 有学到Vertical circular motion 吗? |
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发表于 27-7-2010 11:28 PM
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got. I dun understand why you mixed up the T and the weight? |
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发表于 27-7-2010 11:32 PM
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T/2 refer to what and why you add up T/2 and weight of ball for upper tension? |
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发表于 27-7-2010 11:59 PM
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[img] [/img] |
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发表于 28-7-2010 12:01 AM
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发表于 28-7-2010 01:07 AM
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发表于 28-7-2010 01:18 AM
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Exercise 5.1
Q1 and 2.
vick5821 发表于 28-7-2010 00:01 
第二题我做到的答案跟提供的不一样
所以小弟无能为力咯~ |
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发表于 28-7-2010 10:00 AM
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本帖最后由 vick5821 于 28-7-2010 10:18 AM 编辑
回复 331# 数学神
why can do it like that??? no need see the whole system meh?? now u r doing seperately wor
I dun understand why can do it seperately. |
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发表于 28-7-2010 02:45 PM
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回复 数学神
why can do it like that??? no need see the whole system meh?? now u r doing s ...
vick5821 发表于 28-7-2010 10:00 AM
这种force system好像是要做成free body的
书是这么写的
这样比较容易来分析 |
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发表于 28-7-2010 02:57 PM
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isnt that we must consider that all force in y-component =0 and all forces in x-component =0??
but if do it like that , I dun understand. |
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发表于 28-7-2010 11:05 PM
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回复 335# vick5821
首先要resolve the vector into equilibrium
有两种:
- resolve horizontal & vertical component
- polygon of forces
希望你看得明白....
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发表于 28-7-2010 11:12 PM
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The system can draw 2 seperate triangle de?? I thought all force must be in one polygon? |
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发表于 28-7-2010 11:32 PM
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回复 337# vick5821
做么不可以哦? 那个system is make up of two components
建议你参考Newton's 3rd Law of Motion |
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发表于 29-7-2010 12:01 AM
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本帖最后由 vick5821 于 29-7-2010 12:07 AM 编辑
what relationship with newton third law?? haiz..mine to explain further? |
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发表于 30-7-2010 03:49 PM
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I understand le..can draw two triangle because got 2 equlibrium point..hehe
next ques.
A cnstant torque of 100Nm is used to rotate a grinding wheel. The moment of inertia of the wheel is 70 kg m2 and the system starts from rest. Determine the power deliver to the wheel in 60s. |
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