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dan815
 one year ago
Best ResponseYou've already chosen the best response.5okay lets do AB first, a vector can be written in terms of its change in x and y AB=<x,y> or xi + yj

dan815
 one year ago
Best ResponseYou've already chosen the best response.5AB=<15,12> or 15i+12j are you okay with this

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0yeah so the vector of F is < 180cosx, 180 sinx>

dan815
 one year ago
Best ResponseYou've already chosen the best response.5now for B take the cross product and its magnitude

dan815
 one year ago
Best ResponseYou've already chosen the best response.5thsi is actually going to tell you the torqure experiences at joint A

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0i did the cross product of AB x F and got <2700 cosx, 2160sinx>

dan815
 one year ago
Best ResponseYou've already chosen the best response.5take the magnitude of it now

dan815
 one year ago
Best ResponseYou've already chosen the best response.5ill check ur cross product in the mean time

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0actually cross product is 2700sinx, 2160cosx

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0my bad, typed it in incorrectly

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0since there is a variable, i cant take the actual magnitude, im left with \[\sqrt{7290000\sin^2x+4665600^2x}\]

dan815
 one year ago
Best ResponseYou've already chosen the best response.5ya the cross results in <0,0,(15*180sinx  12*180*cosx)> so the magnitude =(15*180sinx  12*180*cosx)

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0there is suppse to be a sin after4665600

dan815
 one year ago
Best ResponseYou've already chosen the best response.5be careful with the cross product you arent doing it properly

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0what did i do wrong?

dan815
 one year ago
Best ResponseYou've already chosen the best response.5the cross product will result in a vector that is perpendicular to both of these vectors which has to be only in the k or z direction, as both of these vectors are in the x,y plane

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0i thought since we are 2d, we assume there is no k. is that my mistake? i should place a 0 in k?

dan815
 one year ago
Best ResponseYou've already chosen the best response.5wait what formula for cross product did u learn theres 2, one with the matrices and the other one is ABXF = AB F * sin theta

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0how does finding the magnitude of a mean i find the orthogonal vector?

dan815
 one year ago
Best ResponseYou've already chosen the best response.5ABXF = AB F * sin theta

dan815
 one year ago
Best ResponseYou've already chosen the best response.5im a little lost right now lets do b over

dan815
 one year ago
Best ResponseYou've already chosen the best response.5you have AB and F right

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0so lets take the cross product.

dan815
 one year ago
Best ResponseYou've already chosen the best response.5AB X F = AB * F sin theta

dan815
 one year ago
Best ResponseYou've already chosen the best response.5what did u get for the angle between these fectors

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0you arent suppose to get an angle. the answer is left in terms of theta

dan815
 one year ago
Best ResponseYou've already chosen the best response.5yes that is fine give it to me interms of the angle

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0what do you mean interms?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0btw, the answer to b is 225sinx+180cosx

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0theta 2 is 38.7 degrees

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0theta 1 is not given yet.

dan815
 one year ago
Best ResponseYou've already chosen the best response.5it will be interms of that theta

dan815
 one year ago
Best ResponseYou've already chosen the best response.5put these 2 vectors together and using that cross product formula

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0okay, AB x F that means we get 15*(180sinx)  12(180cosx) which simplifies to 2700sinx+2160cosx agree?

dan815
 one year ago
Best ResponseYou've already chosen the best response.5yea u can do it that way too

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0yeah can we do it my way, because that is how the teacher taught us in class.

dan815
 one year ago
Best ResponseYou've already chosen the best response.5both these expresison are equivalent

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0so now that i have my cross product vector, how do i find the magnitude?

dan815
 one year ago
Best ResponseYou've already chosen the best response.5u already have hte magnitude

dan815
 one year ago
Best ResponseYou've already chosen the best response.5becaause there is only a z direction component

dan815
 one year ago
Best ResponseYou've already chosen the best response.5your vector from the cross product was <0,0,2700sinx+2160cosx>

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0so how do i go from my cross product answer to 225sinx+180cosx?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0because that is the answer, apparently from the back of the book

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0really? okay. sp i guess ive had the answer the whole time, lmao. thanks for assuring me i had the right answer.

dan815
 one year ago
Best ResponseYou've already chosen the best response.5wait i want to check something

dan815
 one year ago
Best ResponseYou've already chosen the best response.5what are the units for lb

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0im not sure, i dont think the units are relevant

dan815
 one year ago
Best ResponseYou've already chosen the best response.5there a feet in there though right

dan815
 one year ago
Best ResponseYou've already chosen the best response.5u might have to rewrite 12 and 15 in feet see what that givesu

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0google it, im not sure.

dan815
 one year ago
Best ResponseYou've already chosen the best response.5oh hehe the answer at the book is right :)

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0i have to convert in to feet?

dan815
 one year ago
Best ResponseYou've already chosen the best response.5ya so the 12 is 1 and the 15 = 15/12

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0why is it that the answer does not have any i or j or k?

dan815
 one year ago
Best ResponseYou've already chosen the best response.5gives u the asnwer of book

dan815
 one year ago
Best ResponseYou've already chosen the best response.5remember the cross was only in the z direction

dan815
 one year ago
Best ResponseYou've already chosen the best response.5and we took the magnitude of it , so no more directions

dan815
 one year ago
Best ResponseYou've already chosen the best response.5http://www.wolframalpha.com/input/?i=%3C180cosx%2C180sinx%3E+cross+%3C15%2F12%2C1%3E check ur answer

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0so the answer is a scalar quantity?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0all i did was do cross product, which is a vector, not a scalar quantity.

dan815
 one year ago
Best ResponseYou've already chosen the best response.5magnitude of any vector is always scalar

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0i havent taken the norm of anything yet.

dan815
 one year ago
Best ResponseYou've already chosen the best response.5lets say i give u a vecotr <a,0,0>

dan815
 one year ago
Best ResponseYou've already chosen the best response.5what is the length of this vector?

dan815
 one year ago
Best ResponseYou've already chosen the best response.5right.. now the cross product resulted in a vector with <0,0,a>

dan815
 one year ago
Best ResponseYou've already chosen the best response.5where a was that expression..

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0ahhhh i see what you mean.

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0okay thanks for your help and the great idea of converting to feet!

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0was this question interesting like how you asked? ;)

dan815
 one year ago
Best ResponseYou've already chosen the best response.5well lol maybe part d is better

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0i havent gotten there yet, so ill let you know.

dan815
 one year ago
Best ResponseYou've already chosen the best response.5i kind dont know lb is actually, we use the metric system here

dan815
 one year ago
Best ResponseYou've already chosen the best response.5u know how newtoms is m*a so for us its kg*m/s^2

dan815
 one year ago
Best ResponseYou've already chosen the best response.5you guys use lb instead of newtons

dan815
 one year ago
Best ResponseYou've already chosen the best response.5F=m*a for you i guess its pounds * f/s^2 remember that from now on

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0yeah haha thanks for the advice!

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0yeah im not really sure how to approach part d. im assuming we have to somehow make a 90 degree because thats what maximizes torque.

dan815
 one year ago
Best ResponseYou've already chosen the best response.5yep but they want u to prove with optimization

dan815
 one year ago
Best ResponseYou've already chosen the best response.5so do it with derivatives first

dan815
 one year ago
Best ResponseYou've already chosen the best response.5to check u will see that the angle theta makes is 90 degrees with AB

dan815
 one year ago
Best ResponseYou've already chosen the best response.5do with with derivatives and then do it with geometry and see if they are equal

dan815
 one year ago
Best ResponseYou've already chosen the best response.5Moment = 180 cos(x)225 sin(x) max moment happens when?? solve for 0 <x<2pi radians

dan815
 one year ago
Best ResponseYou've already chosen the best response.5remember what happens at maxs??

dan815
 one year ago
Best ResponseYou've already chosen the best response.5the derivative goes to 0

dan815
 one year ago
Best ResponseYou've already chosen the best response.5make sure you have the max and not min though

dan815
 one year ago
Best ResponseYou've already chosen the best response.5180 cos(x)225 sin(x) = another sinusoid so u will have to solve your angle with in the bounds of 0 to 360 degrees or 0 to 2pi radians

dan815
 one year ago
Best ResponseYou've already chosen the best response.5remember this form, it might be better to use that here now dw:1440399289233:dw

dan815
 one year ago
Best ResponseYou've already chosen the best response.5just giving u alternatives both of them are jut as viable
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