there is a contest to build an electric motor for which we can get some bonus points on the final in my E&M class. they give us a very limited kit and we can only use what comes in the kit which is a couple pieces of thick poster board, 6 feet of insulated wire, a couple paper clips, a couple...
I haven't been able to get any file sharing programs to work with my computers connection. I'm using a school connection - T1 I think. I've tried Limewire, Ares, and WinMX. I got WinMX to connect and search, but nothing would download - they all just said Waiting for network response and then...
Can you elaborate on this?
I haven't yet studied quantum physics, but to my knowledge we don't really know for sure what light actually is, only that sometimes it behaves like particles and sometimes it behaves like waves.
I admit I didn't read the whole thread cause I'm feeling like a lazy ass tonight, but I saw a lot of math, and in physics I like to think about why things occur without using equations. Of course you need them to get exact answers in problems, but its nice to just think about the concept to see...
This may be wrong, but here's how I imagine it:
The sun provides a certain centripital force with its gravity, which changes depending on your distance. If a planet comes along and it is moving with a certain velocity and has a certain mass, you could do the math and figure out the radius of...
I have some crystallized sodium hydroxide drain cleaner that I want to use on my bathroom sink drain, but I just put in a plastic drain and the trap is plastic as well. The clog is past the trap, somewhere deeper. So will the NaOH be alright with the plastic? Not sure exactly what kind of...
The idea popped into my head today of building an extreme telescope (larger than hubble) to orbit an outer planet such as Jupiter etc.. I'm thinking that with it being past the asteroid belt, we would be able to see farther and clearer than with the hubble. Is this an accurate assumption? The...
I took the barlow out and it works pretty good now. Not a perfect image, but it's cloudy tonight so it seems to be working good. Which eyepieces are for higher magnification - long or short focal length?
I decided to dust off my old telescope to see what I could see. I was looking at the moon and messing around, but I could only get a sharp image with the eyepiece removed. Without the eyepiece, I can focus in a good image with my glasses on or off, but with it in it is only a blob of white...
whozum, I see what you're saying now.
James, I understand now. My physics teacher didn't do a great job of clarifying. Also, I misread some of the class notes about it. The first formula I gave is the correct formula for difference in GPE, \Delta U. The second one is for the specific...
whozum, you can't set a = 0 because the this gives you an improper integral. This also implies that the two objects, if allowed to "fall" toward each other, could become infinitely close, which is impossible. To find the GPE of the object at some distance, you have have some reference point...
The gravitational potential energy (U) of an object, from some reference point - such as the surface of the earth, is defined as the amount of work required to move the object from the reference point to its position.
The force of gravity is given by:
F = -\frac{GMm}{r^2}
where r is...
I have a few years of physics experience, and as I was thinking about a few things the other day, something about the concept of torque seemed a little weird to me.
Simple Forces are easy to understand - gravity pulls down on an object, the ground pushes back up with an equal and opposite...
What if the electrodes had a non conductive sheild? You have one set of electrodes to create a spark to ionize the air, and a second set with the insulating coating that don't create current but just create a static electric field. Would the insulated electrodes hold the ions and electrons apart?
Say that you are continuously creating plasma with some sort of sparking device. How strong of an electrical field is required to keep this air in its ionized state, compared to the field needed to ionize it initially?
i see where i went wrong, whoever said torque is a function of time, is right. well it depends on angle as well as time, but i assumed it depended on angle alone. however, since it is already moving faster towards the bottom of its fall, it experiences this torque over a shorter time interval...
hmmm...i was looking through the books proof of the regular formula and where they assumed that sin (theta) = theta, i left it in and ended up with a pretty simple formula that should work for all angles:
T=2*pi*(L*sin(theta)/g*theta)^(1/2)
i put this into my excel table and compared it...
the torque is really only dependent on the angle the pendulum is at (max when horizontal and zero when vertical). it does change with time but the change isn't caused by the time change. i computed the average by integrating torque as a function of theta from zero to the starting angle, and...
what is flawed with my calculation of the average torque? I just have basic physics knowledge, and my highest math is calc2, so your eliptical integral went over my head, a lot of the stuff in your first formula is unfamiliar to me - starting at the first subscript 2, I am not sure what the...
im disregarding all friction or any other dampening force. even with a larger angle it would still oscillate with a constant period and amplitude etc. so it is still SHM, it just can be described by the common pendulum formula because the error would be to great. Since even at small angles, my...
We are talking about SHO in physics and the forumula for period T of a pendulum was introduced - T=2*pi*(L/g)^.5 where L is the length of the pendulum arm/string and g is acceleration due to gravity. the instructor also said this was an approximation that was only accurate for small angles...
ok you know that centripital force is given by F=mv^2/r right? since the bike is traveling in a horizintal circle, the centripital force has to be a lateral force towards the center of the circle. the only lateral force between the tire and the road is friction. in the vertical direction you...
ok, there are 3 parts to the problem:
1) vp=?
2) va=?
3) rp/ra=?
once you have vp, I could easily find the other 2. i was surfing around the internet and happened to find that vp=54200m/s, which i plugged in and it was correct. then i calculated that va=963m/s and that rp/ra=0.0178 which...
ok using the formula v= (GM(2/ra - 1/a))^.5 i can find va if i calculate a, since i already know ra.
I used kepler's law of periods to calculate a=2.68*10^12m
I plugged that back into the formula along with ra to calculate
va=752m/s , which the computer says is wrong
do you guys get...
Using conservation of angular momentum relative to the Sun, find the ratio of the comet's perihelion distance Rp to its aphelion distance Ra from the values of vp and va.
since distance of closest approach - perihelion distance and the aphelion distance are given, you would just divide the...
Use the following data to calculate the speed vp of comet Halley at perihelion. Comet Halley orbits the Sun with a period of 76 years and in 1986 had a distance of closest approach of 8.90×1010 m and an aphelion distance of 5.30×1012 m.
I'm stumped so far on this one. I'm assuming the...
My thought processes:
314*159
314*100=31400
314*50=31000/2=15700
31400+15700=47100
300*9=2700
47100+2700=49800
10*9=90
49800+90=49890
9*4=36
49890+36=49926
But I did it much quicker the other day when I wasn't as tired
I just thought:
Hey, 314*159 = 49926 :)
If you think...
Yes all the forces are in the same direction because all the pieces are traveling the same circular path. I say if the wheel is not rigid enough, it will bend on all sides like a bowl when you spin it fast enough. consider a piece on the edge (top, bottom, or sides). each piece needs a...
The force is equal to the weight of a hanging mass. This doesn't mean that there is actually a mass hanging off of it, it means there is a constant force applied of 8.142N.
Once you see that the problem is simple.
You have the equation T=I*alpha
alpha is angular acceleration which is what...
I thought about it for a while and I think I've got it now. Imagine the gyroscope wheel not spinning, and you try to spin the body in the horizontal plane. As you spin it faster and faster, there is a force on the top and bottom of the wheel (as well as every other part but just to keep it...
I found the essay that you got those pictures from, its a good essay, but the part it talks about the curved path of the 'chunks' of the wheel confused me. It was said that the path of the top part caused a centripital force needed which then causes a reaction force in the opposite direction...
(to eliminate confusion, I am talking about the case of the drawing you just posted where you are trying to rotate it horizontally and it rotates down instead) ok, so your saying that the force vector needed for the chuck points perpendicular to some empty point where there is nothing, so the...
If the plane of rotation of the wheel is turning, it seems like the centripital force would still be provided by the wheel itself since the axis of rotation is still at the center of the wheel (if you hold both ends and push up on one and down on the other).
Ok, that makes sense, I've seen that before. If you push down on a spinning gyroscope, it does go down but then it starts going sideways. So this vector notation doesn't truly explain it because it doesn't account for nutation.
So when you push on the gyroscope and it initially moves...
Oh ok, now I see how it works out in terms of the vectors, the angular momentum vector is horizontal, let's say to the right at a certain point. At this point the torque vector is still in the horizontal plane, but perpendicular to the L vector, which causes the direction to change - the vector...
Precession for me is one of the most confusing and interesting concepts in physics so far, I've thought about it a lot and I still don't have it all figured out. Here's an interesting question:
Consider a gyroscope that has the axle in a horizontal position and spinning so that the angular...
they are asking you for the precessional angular velocity which is mgr/L. where r is the length of the rod that the wheel is on. I got this straight out of a physics book, I haven't worked through it to understand how they derived it but it works. punchlinegirl, where do u go to school at, I...
Thats what I did, the first time it was wrong, I just tried it again and now its right...figures.
It doesn't matter if the bar is vertical or horizontal, all you need to know is that the clay is coming in perpendicular to the bar.
On a frictionless table, a glob of clay of mass 0.38 kg strikes a bar of mass 1.76 kg perpendicularly at a point 0.12 m from the center of the bar and sticks to it.
If the bar is 0.66 m long and the clay is moving at 5.7 m/s before striking the bar, what is the final speed of the center of...
A uniform billiard ball with radius R= 7.00 cm rests on a billiard table. At one moment, the ball received a hit from the horizontal direction. Hit point is h above the center of the ball. Then, the ball begins to move with a velocity V0= 15.0 m/s. The kinetic coeffient between table and the...