Recent content by turandorf

Homework Statement An electronic point source emits sound isotropically at a frequency of 3000 Hz and a power of 34 watts. A small microphone has an area of 0.74 cm2 and is located 158 meters from the point source. a) What is the sound intensity at the microphone ? b) What is the power...

Homework Statement A brass tube of mass 20 kg and length 1.1 m is closed at one end. A wire of mass 9.6 g and length 0.4 meters is stretched near the open end of the tube. When the wire is plucked, it oscillates at its fundamental frequency. By resonance, it sets the air column in the tube...

OK so i pivot around point B. So the weight of the painter times the distance past B has to equal the center of mass times the distance to B which would be 2 m right? Or is the center of mass including the painter as well as the board? I really am confused, sorry.

Oh nvrmind I got it! Thanks anyway!

Thx! That really helps! But how do you convert 1:5.28 to a fraction part of the whole? Haven't had to do this in a while. :P

Oh wow yeah can't see why I couldn't figure that out. (It equaled 294.3N) Thanks for the insight! So in (b), the torque of the man can't exceed 294.3(4+x), right? (Where x is the distance from the support to the painter and the 4 comes from the distance from point A to B.) Then if the torque pf...

For (a) the weight is (100+60)9.81=1569.6N (man+board) Is this just split between the two points? Or do I have to use Torque=F(r)? (in which case r would be 4 meters [distance between B and A] right?)

ok thanks to all for the help! You all are grade-savers!

So did you end up with an equation that looked like (sin(Θ)/sin(Φ))cos(Φ)(6.9-x)=cos(Θ)x ?

Ok that makes sense but I am confused by the system of equations. Usually one of the tensions is possible to find in a numeric form. But since we do not have the mass, how is that possible?(eg. T2=(T1sin(Θ))/sin(Φ) but how do you find T1?)

So you would get EA(F1/AA)=2.2EB(F2/2.4AB). When I solve for F1, I get (.2EB(F2/2.4AB)/EA)*AA and F2=((EA(F1/AA))/(2.2EB))*2.4AB. Not sure where to go from here. And I'm not sure how to convert a ration to a fraction. Thanks for helping btw.

So what part of T2(cos52)(6.9-x)-T1(cos39)(x)-mg(3.45-x)=0 or the other equations still work if you use the center of mass as a pivot point? I also am confused about the mass, as it is not given and you need it to find tension. If anyone could explain that would be great! :)

Homework Statement A physics student of mass mm = 100 kg gets a summer job painting houses. On his first project, he builds a platform using large pine board with a mass of mb = 60 kg The board has an overall length of L = 8.5 meters and set on two 1.1 meter tall saw horses so that l = 2.25...

I'm having trouble with this one too. I know that the change in length of one equals the change in length of the other which means y1(F1/A1)L=y2(F2/A2) where y=Young's mod, F equals the force of gravity, L equals the total length of the brick, and A equals the area. So using the given numbers...

I seem to be stuck on this part now e) Let's say that instead of the coal falling out of the bottom of the coal car, some very strong physics student threw it backwards from the car, so that the velocity of each piece of coal was zero just after it left her shovel. How fast does the car travel...