A real noodle baker (vector problem)

[Sebastian]

I've been trying to solve this equation for a while now, and for the life of me I can't get it. If you can help, please do so. you might just learn something in the process. So here goes:
A collar that can slide on a verticle rod is subjected to the three forces shown. Determine (a) the value of the angle a(alpha) for which the resultant of the three forces is horizontal. And (b) the corresponding magnitude of the resultant.

Heres an image of the figure:
[url=http://imageshack.us][img=http://img183.imageshack.us/img183/967/mvc009xza4.jpg][/URL]

 

[Hectic Glenn]

Image doesn't work, when you host it, pick the bottom of the 4 links they provide.

*whistles for kirov/ ikerous for mathy/physics questions*

edit: worked it out now i see!

 

[Ennui]

hate hate hate physics

 

[Sebastian]

hate hate hate physics

Physics is your friend. It's the only class where I get great satisfaction from figuring a problem.

 

[Ikerous]

To get alpha solve 90 + 70sin(a) - 130cos(a) = 0
I dont have a calculator w/ me
It should be easy to find the magnitude once you have alpha

And yes, physics r0x0rs

Edit:
Alpha = 24.14 degrees
Magnitude = 117.05 lb

 

[Sebastian]

To get alpha solve 90 + 70sin(a) - 130cos(a) = 0
I dont have a calculator w/ me
It should be easy to find the magnitude once you have alpha

And yes, physics r0x0rs

Edit:
Alpha = 24.14 degrees
Magnitude = 117.05 lb

Why did you solve it like you did? Did you break it up into it's components or something?

 

[Ikerous]

Yea, if the resultant vector is horizontal, that means theres no y component
So just take the y-component of the vectors and set it equal to zero to get alpha

Then to get the magnitude just sum up the x-comps w/ that value of alpha

 

[Sebastian]

Just one more question dear sir: How the deuce do you solve 90 + 70sina - 130cosa = 0?

 

[Ikerous]

Graphing calculator :|

 

[Que-Ever]

I thought this thread would be about a man who baked noodles Math threads are more irritating than girl help threads.

 

[Ikerous]

Girl help threads = crap
Math > *

 

[Sebastian]

Graphing calculator :|

How zu say I have no graphing calculator. If its a bunch of work, I'll just ask it to the professor at school tomorrow. Anyway, thanks for the assistance.

 

[Que-Ever]

Girl help threads = crap
Math > *

Math makes my testicles shrink.

 

[Ikerous]

How zu say I have no graphing calculator. If its a bunch of work, I'll just ask it to the professor at school tomorrow. Anyway, thanks for the assistance.

If you dont have a graphing calc you can use a formula

If you're solving asin(x) + bcos(x) = c for x, you can use

x = arcsin(c/(sqrt(a^2+b^2))) - arctan(b/a)
(<3 Dan for figuring that out for me once)

In this case a = 70, b = -130 and c = -90. Then convert the answer from radians into degrees. A graphing calc is a lot easier tho

 

[Sebastian]

If you dont have a graphing calc you can use a formula

If you're solving asin(x) + bcos(x) = c for x, you can use

x = arcsin(c/(sqrt(a^2+b^2))) - arctan(b/a)
(<3 Dan for figuring that out for me once)

In this case a = 70, b = -130 and c = -90. Then convert the answer from radians into degrees. A graphing calc is a lot easier tho

The nail in the coffin. Thanks a bakers dozen. Now I can go to school tomorrow, shouting from the rooftops that I have the answer and pwning all the noobs. Maybe I'll sell the answer and send you 25% of the profit. Anyway, heres to the richness and fame that i'll atain from this answer.

 

[Ikerous]

Np, <3 math, hf

 

[Ikerous]

Anyone wanna try my physics hw?

It's a projectile motion problem. Theres a projectile w/ innitial velocity v. The ground is raised at an angle alpha, and the projectile is launched at an angle of theta. What value of theta in terms of alpha will maximize the range of the projectile.

Diagram

 

[Dan]

I'm pretty sure I have that exact problem somewhere in my first year engineering physics text. The funny thing is that at my job, my boss gave me a real life question like this for balancing moment forces on a 1700 lb tank attached to a sliding support rod. Apparently real life engineers don't practice this so when they do get these problems they give it to the students.