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18h
comment How gravitational waves are exactly produced?
Just to point out, when someone gets around to answering this question, you should be convinced that we do emit gravitational waves, as long as are we are moving in the right manner!
Feb
7
comment Do physical entities with one dimension equal to 0 exist?
Yes I totally agree, but I would argue that the center of mass of the Solar System is not a "physical entity". It's just the mathematical description of something. If you are willing to include anything which has physical relevance as an "entity", then yes, these things do exist and have dimensionality less then 4 (zero, in the case of a single point).
Feb
6
reviewed Approve Voltage of a battery in a circuit with an infinite resistance
Feb
6
reviewed Reviewed Understanding parallel plate capacitors
Feb
6
comment Understanding parallel plate capacitors
As per the homework policy, you will have to give us a bit more information about what you tried before we can answer. I'll say this though - you have an equation which describes capacitors, and a description of a process happening to a capacitor (area changing from 0 to max and back to zero). The equation is always true (at each area), so as the area changes, what does the equation say happens to the charge?
Feb
6
reviewed Reviewed How to calculate power necessary generated from wind turbine to run a motor
Feb
6
comment How to calculate power necessary generated from wind turbine to run a motor
In principle this is a very good question, but it seems like we will need quite a bit more information. Like, angle of the rotor with respect to the wind, weight of the rotor, torque required to move the brushes, etc.
Feb
6
comment Time Dilation and the direct opposite
haha ok I see what you're asking now. The problem is that the basic tenet of relativity is there is no "background coordinate system" for us to say we are at rest with respect to. That's literally what the "relative" in "relativity" means, we can only measure speed with respect to something else, never absolutely. From your perspective, you are not moving, everything else is moving around you. Since you do have mass, your approach is inconsistent.
Feb
6
answered Time Dilation and the direct opposite
Feb
6
comment Do physical entities with one dimension equal to 0 exist?
@danielAzuelos: Yes, that's part of why I said they are NOT actually null-sized. Mathematically we characterize them as such, but photons interact via the long-range E/M force. Since their interaction range is not 0-dimensional, they don't act like 0-dimensional object.
Feb
4
revised Which force to resolve?
used a strange coordinate system, like a dope!
Feb
4
revised Which force to resolve?
deleted 1 character in body
Feb
4
comment Which force to resolve?
Ok this is fine, but $mv^2/r$ is not a force (although you refer to it as such right below your picture). This is like the #1 thing students get wrong in Physics I. You are not equating forces, you are using Newton's second law, $\sum F= ma$. Why is the acceleration even there? Because $R$ is making it acceleration towards the center! /rantover
Feb
3
answered Do physical entities with one dimension equal to 0 exist?
Feb
3
answered Which force to resolve?
Feb
3
comment Resultant force and constant velocity
because it had some initial velocity. Or, put another way, in order to get the car moving at all you can't have $\sum F=0$. To accelerate away from zero you have to apply more force in the forward direction then is opposing you in the opposite direction. Once it's moving, you can decrease the force you apply to match the opposition force, and move at a constant rate.
Feb
3
answered Resultant force and constant velocity
Feb
1
reviewed Approve Force required to swing gate open/close
Jan
31
reviewed Approve What happens when the switch in this circuit is flipped?
Jan
29
comment Question about Kinetic Energy and Force acting on a body
Yup that's totally right - from $x_1$ to $x_2$ there is no force on the object, so the velocity is constant, which means the KE is constant. When it reaches $x_2$ the kinetic energy begins to increase again.