Suppose we have a cylinder with one wall guard by a demon. Inside is one gas molecule moving left and right for simplicity.
Now we want to closer the wall (compress the gas) without doing work. The job of the demon is push the wall closer when the gas move left and lock the wall when the gas...
But there is current through it. Each time the switch close, current flow to speed up the wheel. Each time current flow to the 24V, curren flow slow down the wheel. Each cycle, there is a speed up and slow down. The net is zero current with is steady state.
Unload motor require current to overcome friction. Loaded motor require current for the load. We assumed ideal, no friction, so the only requirement is current for the load.
Hm... you might have read the diode wrong. The bottom 24V has diode that only allow current for charging direction . The bottom 24V cannot be the supply. When the switch close, current is draw from the 12V through the coil, speeding up the wheel. Then the switch open, it'll close again on...
The current input has to be equal to current output have steady state speed. If there is only input current, the wheel would keep speeding up. And when we draw output current, that is a load. Charging battery is a load.
Base on the replies I think the answer is yes. Let's assume that everything is ideal. The current going into the magnet - current induced by magnet = 0 for steady state. Let's assume all batteries are 12Vs.
So from the input we have IV = current of 12V x 12V = Power input
From the output...
Well, my main purpose is to see if we can attain an EMF greater than the supply voltage. When the magnet pass by the coil, let's say it's supper fast that exceed the supply voltage, we aren't apply voltage to the coil because if we do, the magnet slow down in transfering energy to the supply...
Yes, I guess we have to assume the coil can be on instantly without being choke. What I'm trying to say is can we attain EMF greater than the supply voltage.
As I drew in the voltage waveform, when the magnet change direction from incoming to outgoing, the back EMF is so small that we can inject current into the coil. Of course the wave form get bigger as speed increase, so we have to shorten the ON time of the coil. But we can always inject...
Thanks guys. I did the experiment and measurements. And the result is conservation of energy win, again. Efficiency is around 40s%. I turn the wheel upside down and efficiency doesn’t change much. So yes, you guys are right. Sorry giving you a hard time Dale. I should have done this before...
If the wheel is moving at 1m/s, imparting a force while moving is equivalent of throwing at rock at greater than 1m/s and transfer energy. Matter of fact, let make the wheel move at 100m/s. You have to throw rock faster than that. Let's say the station pusher throw rock too to move the wheel...
oh? Let's say we have 10 pushers station along the path. The wheel translate at 1m/s. The pusher push on material moving at small v(almost zero).
P=Fv x 10
Or we have one pusher moving at 1m/s also push on the material moving at small v.
P=Fv x 10 + F(1m/s)
It is a big difference.
I think there're two methods to replace the tension force on the wheel.
One is you have to station pushers along the path the wheel travel and each time the wheel pass by, each pusher going to push the wheel.
Second is you only need one pusher, but he must chase the wheel to impart a...
So there is no different between motion of material or motion of the force here because they're both exactly the same. What about if you're on a train moving right at 1 m/s and pushing a mass left. When the mass reach 1m/s left. What is the mechanical power? Fx1m/s or 0?
Let's say you're right that the motion of the material is important. How can you be sure that that at time t+delta(t) it will be the same as the time t? The point of material also move upward and at time t+delta(t), or half delta(t), the force already jump to the next point in the arc.
Suppose you're a point on the floor and a block mass slide pass you. The block mass said " I have friction acting on me during my motion so the mechanical power is friction x my speed". When ask the point on the floor, it said "well, I don't have motion so there is no mechanical power". Yet...
Thanks guys. I just don't get where I misunderstood things. Of course I would continue to prove or disprove myself when I have a chance.
My thought is instead of a tension force pulling on the wheel, you can imagine yourself running and pushing on the same point on the axle. Now compare...
The only solution to our argument is to let the block drop a height h, after height h, measure the rotional energy of the wheel, the translational energy of the wheel, and the kinetic energy of the weight. If it add up to the drop height potential, then I submit.
You're only half correct. Consider the case of a block mass moving through a flat friction surface.
Yes, there is the motion of the block at the point of application of the friction force, a relevant quantity.
But, there is also the motion of the point of application of the friction force...
Here I drew the the system. The cylinder moved a distance D at a later time. The force (in red) moves the object for a distance D. The weight on the right also displaced a smaller distance d.
work done by the weight = mgd
work done on the cylinder = mgD
Not really, if you think a force moving through space, both ends have the same force moving through different space length. That's why the string wound up, to compensate for the translation movement.
Let's say I was pulling the string. I felt a tiny displacement. So my work done is the force I pull times the displacement my hand made. On the cylinder end, the same force carry by the string, but the displacement is many times higher. The work done is then force time big displacement...
I can understand spring does work, but string doesn't store energy. Work is force x distance, so one end of the string the displacement is zero. The other end of the string, it displaced with the cylinder through space. But what is the source of energy?
I think what intrigued me about this is that I often think when the wind hit a windmill, the blade turn with the wind. It baffles me when the blade turns the opposite of the wind. So here I drew up a system of how we can make the blade turn any direction.
we have blades and a large wheel...
Suppose we have the mass and string orbiting like the outer ramp. Then we pull the string to achieve the inner ramp orbit. We can say that the the axis never changed. Can we then make the ramps exactly as the path of the string and consider the axis never changed?
the stretched slinky, when unstretched, provides the force.
It's resembled. The second mass still move in circle even when the first mass disconnected because pressure wave need time to reach the second mass.
yes, slinky are masses and springs connected in series. What I meant by delay momentum is slinky action redistribute the center of mass without an external force. If you see a slinky drop from a rooftop, the top part fall down faster, which means the center of mass change as it drop.
After...
We have two masses hitting the train north, so the speed increase. However, after rethinking about the slinky mass (since mass is require for a force) has momentum component heading south. The overall speed of the train remain the same. But the interesting thing I'm thinking is can we...