Recent content by David112234

But even if it is not attached shouldn't it still cause the plane to go forward by Newtons 3rd law. 2 magnets one larger than the other would be a better example of what I mean rather that rope. so do I subtract the velocities of the air befre and after the jet? This only makes sense to me if...

Still kind of confused, so since it is also shooting out air I will add an dm_{air}(v-u) dp = (v+dv)(m-dm) + dm(v-u)+dm + dm_{air}(v-u) - mv but how does this take into consideration that it is also sucking in air at the front? If it is sucking in air it should contribute some forward momentum...

I am not familiar with what ##\delta t## if possible I would like to avoid it, also why integrate at all? Here is the method that am use to. For a regular rocket dp = (v+dv)(m-dm) + dm(v-u) - mv it simplifies to dp = m(dv) - u(dm) dividing by dt dp/dt = m(dv/dt) - u (dm/dt) dp/dt = 0 since...

Not sure what you mean, shouldn't I divide both sides by dt and the left side would be dp/dt which is force? Where do you get impulse? Also before that, the equation I wrote shouldn't I add ( or subtract) something in order to include the intake? What do I do with the intake?

Could you help me derive that formula?

Homework Statement Homework Equations conservation of momentum Thrust of rocket engine = -u (dm/dt) u is the velocity of the gas being expelledAlso found this from Wikipedia, not sure if it is relevant The Attempt at a Solution For these kinds of problems I assume you need to apply...

I suppose both since calculus of variations is how I was introduced to a functional. If ∫√((dy/dx)2+1) dx = L is a functional and ∇operator or curvature function are both functionals, I do not see the similarity between them, the input for ∇ and curvature (K) are vector functions. In order for...

So from doing further research this is my current understanding, a functional comes from the calculus of variations. You have the formula for the length of a curve ∫√(dx2+dy2) = L ∫√((dy/dx)2+1) dx = L So the curve length of a some function = some length. and what ever that function is...

When I asked "And a vector is just written as <a,b> , if you take that as an input isn't it just essentially a regular function of 2 variables? y=f(a,b)" f(<a,b>) = f(a,b) is what I meant, you said "yes" Does my original question mean something else than what I thought I was asking? And I am not...

So a functional is just a special case of a function where the input is a vector and output is a scalar? like Curvature? Does being linear/ non linear has anything to do with it? And if f(<a,b>) is the same as f(a,b) what is the significance of this? Also, I read this topic...

I have read the wiki page (https://en.wikipedia.org/wiki/Functional_(mathematics) but it is not helping. I understand what a regular function is input > do something to that input > output. but not what functional is, Wikipedia says "from a vector space into its underlying field of scalars"...

So now I have understood how a circuit behaves with two batteries, going back to the original problem, at point C why wouldn't you add the voltages from the battery and from the motor? When the motor is creating an EMF don't you have a circuit with two batteries?

I made an error there, the lower picture depicts what I meant to write, So if battery 1 is 10V and battery 2 is 3V wouldn't the current through the resistor be as if there was just 1 (7)V battery instead? And the recharging of the battery, let's assume they don't discharge and are perfect...

Sorry for the late post, I think my problem stems from not understanding behavior of circuits with more than 1 battery Lets ignore the middle resistor and use a series circuit for simplicity So V1 will create a current clockwise, V2 will create a current counter clockwise, which way will...

Ok, so current flows from high to lower potential, from top of the rotor to the bottom. EMF does the opposite, it pushes charges to a higher potential. So the motor would create a voltage at point A, since those wires have the same potential than the potential at A,B, and C would now be Vfrom...