Recent content by Tom_K

How is it different? Let the center of the string on the Atwood machine have some mass then and let that be exactly centered at the top of the pulley when the string goes taut. The other two masses are there only to apply the force and the counter force. You can let them each be 100 kg so that...

In the case of the two 10 kg masses on the Atwood machine, say mass1 is allowed to fall from rest for one second before the string becomes taut. Mass1 will have an instantaneous velocity of 9.8 m/s at the instant the slack runs out, and mass2 will still be at rest on the floor. In order for...

Not necessarily. The block was never moving at a constant velocity; it was accelerating towards you at 9.8 m/s^2 with a net force acting on it so it definitely would not continue moving at a constant velocity. When you introduce the matching force on the left side, there will be a discontinuity...

If I understand your main question, it concerns the difference between a chemical reaction and a phase change, as regards the amount of reactants and products. I am not sure that focusing on ΔG will lead to an answer. A chemical reaction that has reached equilibrium is in a state of Dynamic...

There is a voltage spike across the inductor that does die away as current flows, so in that sense there is an impulse or transient response.

As I see it a chemical reaction requires that the separate components come into contact with one another (mixing) for the reaction to take place and this places another condition upon the process which the phase change does not have. Unless the mixing state is somehow incorporated into the ΔG...

That should have been Btu/hr. 0.3632 Btu/Hr = 0.10643 watts = 0.10643 j/s So sorry to confuse you! turbulent flow in the little 1/16 inch dia hole? Well OK, then! Model it any way that you like, it is still only an approximation. Have fun!

I calculate the change in temperature to be about 1 or 2 degrees F at most, mainly because of the short time that the air will be in the hole as CWatters said. The energy transfer rate is easily calculated using the Fourier conduction equation or this handy on-line calculator and it works out...

Physically what is happening is exactly the same as what happens when a force is applied to a mass to accelerate it. F = ma and VL = L di/dt Electrical inductance is the same as physical or inertial mass and electrical current is the same as velocity, di/dt is acceleration. If you understand...

Yeah, I had one of those brain freezes going on. dE/dt = mva is what I was trying to think of.

I don’t believe I have ever seen the expression dE/dt = Fv before anywhere. I see you had dW = F∙ds/dt and since W = E then dE/dt = Fv But since W = F∙s how can you treat F as a constant when differentiating W? Since F = ma, wouldn’t you need to differentiate the ma term with respect to t...

To be honest, I don’t really understand the “problem” but: Maybe this can be resolved by considering that the displacement of the piano does not happen instantaneously when you apply a force to it. I am thinking along the lines of a mass suspended from a spring and the mass is at the top end of...

Yes, that helps, thank you. It seems the (cB)^2 term can be an analog of kinetic energy in some respect. Then it is easy to see why it will be zero in some frames.I still find it difficult to conceptualize those lines of force vanishing but I am probably over thinking this.

Yes, that must be true because B = μoI/2πr and with no relative velocity between charge and observer, no I and no B. Yet, I am having difficulty conceptualizing this because I learned to think of a magnetic field in terms of lines of force, and these lines can even be shown to exist around a...

If the current is in an electrically neutral wire, (equal number of positive and negative charges) there will always be current flow as seen by an observer from different frames of reference. In the frame where the electrons are moving the observer will detect a magnetic force field and in the...