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Okay I have derived both equations. dR/dx = v*(cos(x)t' - sin(x)t) dH/dx = v*(cos(x)t + sin(x)t') - gt*t' I am unsure where to take these results. Can you help me?

I'm not that familiar with this strategy of differentiation. But I thank you for giving me this new technique to me. I definitely have to try this out, and hopefully master it.

This is an amazing solution. Thanks for taking the time to write this. The source you linked also looked fantastic. Thanks!

Like R = vcos(x)t and H = vsin(x)t - 1/2gt^2?

Thanks for your replies. I did that. But I got the same displacement equation that I posted. t = (vsin(x)+sqrt(v^2*sin^2(x)+2gh))/g. I got this for the time period.

I came up with this problem and did the work, that is hardly an example of low-effort. I don't think I understand the hint well. Do you happen to know the solution?

Can you show me how you would do this problem? You seem like you know what's up.

Sorry about the messy equations. When I took the derivative of range vs angle, I got a very complicated output. Therefore I thought it was difficult to optimize using that solution to find an expression for the angle. That's why I thought there may be a different or better approach available.

I found the function of the range of the projectile launched from a cliff. R = vcos(x)((vsin(x))+sqrt(v^2sin^2(x)+2gh))/g I stopped here because I feel like taking the derivative and optimizing for maximum would spiral out of control. Is there another approach to this problem?

Hahahaha, I was sitting there wringing my brain out figuring out what I did wrong. Now I see. Thank you!

For this problem I tried to find when the binoculars reaches the maximum height. So, (0.75 + 1.28)/2 = 1.015s. Using that information I can solve for the initial velocity. v_o = gt = 9.947 m/s. Then using the initial velocity I can solve for the height of John using the 2nd kinematics equation...

Thanks, that's what I was looking for.

Question.

Yeah. I got it with the trig identities.

Ohh... ok. So it has something to do with the sum and difference identities. Thank you.

theta1 = 90- theta2 I substituted that into v^2*sin(2theta1)/g So I get v^2*sin(180-2theta2)/g Now I'm stuck. What do I do next?

I have a hard time understanding what this problem even means. So I can't even begin with it.

Thank you Greg!

Can someone explain it to me exactly how dimensional analysis works (perhaps gives some examples.) What use does it have? Is it a convenient way to check your solutions? My teacher showed this example E ~ G, M, R [E] = k[G^α * M^β *R^γ] Maybe someone can explain this.

So sorry that I'm bombarding you with questions. I may be repeating myself here. Coming back to the basic scenario of two electrons shot at each other and bounce off. That is what the most basic Feynman diagram represents I think. In classical physics, the electrons are surrounded by an...

So how did Feynman arrive at "electron emits a virtual photon?" And it carries momentum which causes electrons to recoil and deflect off each other.

Ok, I accept that they just do it. But do electrons just go off an emit photons randomly? Or only when a circumstance happens? Is there a pattern to it?

What's the mechanism behind how an electron emits (or absorbs) a photon? How does that work?

Thank you! That cleared up a lot of things.

As an extension question, I read parts of the QED lecture. It said that light can take an infinitely different route, but some routes are more likely for light to take. My question is that how does that idea relate to the Feynman diagrams (where 2 electrons deflect off each other because of a...

So... QED is a better, more detailed explanation of electromagnetic forces? It replaces the field theory? I just want to know what QED is, not what limitation it has.

Yeah. But what IS QED anyways? I'm not really talking about Feynman diagrams. I just want to get a gist of QED and how it relates to Feynman diagrams.

I'm new to QED, so I want to have a general grasp of what's going on. I just want to understand it conceptually. Can anyone explain it in a way so a layman can understand?

The famous example demonstrating that simultaneity is an non-invariant variable would be the lighting bolts striking a fast moving train. Or a projector at a mid-point shooting off two beams at the same time to receivers on the opposite ends (for the person at rest and not on the train's...

For the Minkowski diagram, my teacher used "ct" as the unit y-axis and "x" as the unit of x-axis where x is distance. I presume that c is light speed and t is time for the y-axis. I think they are multiplied together? I thought that speed times time is distance/displacement I'm a bit confused as...

Like I said, I'm new to Special and General Relativity. It really sucks when I space out for 2 minutes in class and for the next 30 minutes I'm completely lost until the teacher brings up a new topic. I'm looking for supplementary materials (online preferably as I'm away from home) that can...

Hi, I'm new to this thread. My brother tried to explain the Schrodinger's cat to me but the explanation was vague, I became confused. Can someone explain to me in high schooler language what it is and how it works? Thanks in advance.

Thanks for the response! I'm planning on working about 30 problems per day each chapter in my textbook. I hope that can fill in my gap in knowledge, and it will click for me. Is that too much or nah?

As I stated in the title, I'm trying to compete at the physics Olympiad and hopefully walk away with a decent ranking. I am currently a sophomore at a mediocre high school; I'm taking this Olympiad physics class for preparation. The course is once a week for 3 hours that is covering...

Thanks for responding!

Oh ok, I see now. I need to substitute that that equation into the first one. So 7 = v2f - v1f v1f = v2f-7 28 = 3(v2f) + 4(v2f-7) v2f = 8m/s Thus v1f = 1 m/s Thank you!

Kinetic energy is conserved? Sorry, I'm a bit lost. Could you elaborate a bit more? Thanks

Homework Statement A 4-kg block moving at 7m/s makes a head-on collision with a stationary block of mass 3kg. Find the velocities of the two blocks after the collision. m1=4kg, vi1=7m/s m2=3kg, vi2 = 0m/s Trying to find vf1 and vf2 2. Homework Equations Using the conservation of momentum...