Could someone could show me where I am going wrong? Here is my work so far.(adsbygoogle = window.adsbygoogle || []).push({});

Given: [itex]F\cdot\nabla t = (5.4 N.s) j[/itex], Density = 1.2

So, [itex]M_{ring} = 1.696 kg[/itex], [itex]M_{rod} = 0.36 kg[/itex], [itex]M_{total} = 3.753 kg[/itex]

Part a) V = 1.44 m/s j (which is correct)

Part b)

Moment of impulse:

[itex]H_{G} = r\times mv = (-0.225 m)\cdot (5.4 kg.m/s) i + (.225 m)\cdot (5.4 kg.m/s) k[/itex]

Mass moments and product of Inertia:

[itex]I_{x} = 2\cdot (\frac{1}{2}M_{ring}\cdot r_c^2 + M_{ring}\cdot r_c^2 + M_{ring}\cdot (\frac{1}{2}\cdot L)^2) + \frac{1}{12}M_{rod}\cdot L^2[/itex]

[itex]I_{y} = 2\cdot (M_{ring}\cdot r_c^2 + M_{ring}\cdot r_c^2) = 4\cdot (M_{ring}\cdot r_c^2)[/itex]

[itex]I_{z} = 2\cdot (\frac{1}{2}M_{ring}\cdot r_c^2 + M_{ring}\cdot (\frac{1}{2} L)^2) + \frac{1}{12}M_{rod}\cdot L^2[/itex]

[itex]I_{yz} = M_{ring}\cdot (0.15)\cdot (-0.225) + M_{ring}\cdot (-0.15)\cdot (0.225)[/itex]

[itex]I_{xz}= I_{xy} = 0[/itex]

[itex]H_x = (-)(.225 m)(5.4 kg.m/s) = I_{x}*/omega_{x} = 0.336*w_x[/itex]

[itex]H_y = 0 = I_y*w_y - I_yz*w_z = 0.343*w_y + 0.114*w_z[/itex]

[itex]H_z = (.225 m)*(5.4 kg.m/s) = - I_yz*w_y + I_x*w_x = 0.114*w_y + 0.164*w_z[/itex]

Solving for w_x: w_x = (- 3.62 r/s) , which is wrong!

I won't bother with the rest.

The correct answer is (-3.55 r/s)i + (-3.2 r/s)j + (9.87 r/s)k

Note: I would use Latex, but it would not preview. Is there a way I can practice this offsite?

Thanks,

Mark

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# Homework Help: Dynamics: Angular Momentum

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