# #physics

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2. ### I Observing a rotating body when approaching it at near light speed

Summary: Will the motion around us become faster when we travel faster? When we approach a body rotating on its axis with certain speed v, will we see the body rotating in speed slightly more than the v during our motion ?And what happens assuming that we are approaching the same body in speed...
3. ### Basic Capacitor problem

Homework Statement Two 5.0-cm-diameter aluminum electrodes are spaced 0.50 mm apart. The electrodes are connected to a 200 V battery. Homework Equations C = εA/d The Attempt at a Solution So for my solution I took the area of the plate, ((.052π) * 8.85*10-12) / .5*10-3 and I got an answer of...
4. ### Do I exert a force on the moon?

Hey, I was wondering. If the earth exerts a force on the moon and the moon exerts an equal but opposite force on the earth (Newton's third Law of motion), do I also exert a force on the moon since I also have mass and therefore, the moon would exert a force on me (equal, but opposite). Also...
5. ### B Tension of a massive rope

[moderator: text edited to change the phrasing.] There is a question that that says: a 50 kg weight is suspended from the bottom part from a rope. If the rope has a weight of 100N. Then what is the tension at each end of the rope( the top part connected to the ceiling and the bottom part to...
6. ### Two blocks, a fixed pulley and friction

Homework Statement a mass m1 is attached to a second mass m2 by an acme (massless, unstretchable) string. m1 sits on a table with which it has coefficients of static and dynamic friction μs and μk respectively. m2 is hanging over the ends of a table, suspended by the taut string from an acme...
7. ### What are the equations of these free fall/drag graphs?

Homework Statement The screenshots of the graphs are attached. The first graph is a velocity graph of a basketball with respect to time, and it is assumed that it has been launched at an angle of 45 degrees and an initial velocity of 10 m/s. Due to air resistance, which I was able to include...
8. ### Programs Physics degrees in the world?

So I'm looking to do a bachelor's degree which involves a lot of physics and math but one that is not engineering, maybe like a BSc in physics? Idk Anyone got any suggestions?
9. ### Other Stuff you should do in undergrad besides studying the course

What should i do during my UG physics course other than following what is taught at college, like doing internships ?
10. ### How many hours per day should I learn physics and maths

Hello everyone, I'm a high school student, currently in 10th grade. I'm going to major in physics, I'm interested in how many hours should I study physics and maths per day to do my best and to be as smart as possible? I don't only want to master high school materials, I also want to learn...
11. ### Programs Does a Masters help me get a PhD position?

Hello PF, So in my country (Lebanon), we have this French system of education where masters come after Bsc. and then you can consider the Ph.D. position. Apparently, this is not the case in the US and one can get into a graduate program with just the Bsc. I know they are equivalent but if...
12. ### Source of error

I have done an experimeny to investigate how the voltage across a capacitor, Vc varies as it charges and to find the capacitive time constant in a DC RC circuits and Study resonance in an AC inductor-capacitor circuit (AC LRC circuit). I am now having trouble in writing the source of error of...
13. ### Schools How can a high school student get involved in research?

I'm currently in high school and interested in physics. I want to get involved in research somehow - whether it be as an intern, or actually conducting a project, so I can expose myself to the process and community. First of all, is this worth it? Will it help me get accepted into a good program...
14. ### Newtonian Mechanics : Rectillinear Motion of a Particle

Homework Statement Find the velocity ± and the position x as functions of the time t for a particle of mass m, which starts from rest at x =0 and t =0, subject to the following force functions: (a) Fx = F0 + Ct (b) Fx = F0 sin Ct Ct (c) Fx = F0e^ct where F0 and c are positive constants...
15. ### Mechanical Physics -- Find the velocity and acceleration of the particle from its position

Homework Statement [/B] The position of a particle as a function of time is given by r(t) = i(1 - e^-kt ) + je^kt where k is a positive constant. Find the velocity and acceleration of the particle. Sketch its trajectory. Homework Equations v (t) = dr/dt a(t) = dv/dt The Attempt at a Solution...
16. ### How can I prepare for Physics Olympiad 2018 in the best way?

Hi ! Please suggest me some preparation methods and books . My relatively strong part is mechanics . I am really looking forward to improve every topic of the syllabus . It would really be awesome if you would guide me with your wisdom . Also , if there are some experiences that you might want...
17. ### Change in temperature for a system with entropy change

Homework Statement I am Pretty Lost with this problem...[/B] A 2.45-kg aluminum pan at 155∘C is plunged into 3.58 kg of water. If the entropy change of the system is 162 J/K, what was the initial temperature of the water? NOTE:We did not recieve a Tf for the system. Homework Equations...
18. ### Find the Coefficient of friction on a banked curve.

Homework Statement A car giving a turn on a curve with 88m of radius, traveling at a speed of 95km/h, the curve is perfectly banked for a car traveling at 75 km/h, meaning that the curve has an angle θ of 26.7º. Homework Equations μ = ? r = 88m v = 26.38 m/s θ = 26.7º Ff = μ · g · m Fc = m...
19. ### How to find the magnitude of Force from an A vs Mass Graph

Homework Statement I have attached the graph which displays Acceleration vs Mass. It shows the acceleration of objects of different mass that experience the same force. I need to get the magnitude of the force from this. Homework Equations F= ma The Attempt at a Solution I used F=ma for...
20. ### Admissions Reapplying to Engineering: Physics II, Calc II Or ODE?

Hello, I just came across this forum and thought of asking for advice! I am reapplying to Engineering and I am taking summer school (Full term) and need to take 2 more classes to boost my avg. Right now, I am enrolled in Physics II, Calculus III, and ODE and I have to choose two out of the...
21. ### Cooling Fan Calculations

Hi everyone! I was wondering if there is a known equation to calculate how the speed of a fan affects the cooling of a heat source. Is there a way to calculate this or know what type of relationship it is? Thanks!
22. ### Programs Preparing for a Physics Degree

As a sophomore in high school, I'm starting to reach that point where I need to think about on my future beyond graduation. I'm currently aspiring for a degree in physics, since math and science are the only subjects I've consistently enjoyed and I'm pretty good at both. Next year I'll be taking...
23. ### Projectile Motion/ Explosion Mid air

Homework Statement So in the problem there is a projectile that is in the air and has no forces acting up, only the -9.8 acceleration down, the projectile is at the maximum height of say 10m and at this height (with a horizontal acceleration of around 40 m/s) explodes into two even 20g pieces...
24. ### How to find Coeff of kinetic friction without mass?

Homework Statement For my Physics lab this is what my teacher handed me... I have no idea how to attack the situation, can someone help solve? Devise a procedure for an experiment which will measure the coefficient of kinetic friction between a block of unknown mass m and the table, where the...
25. ### Stellar evolution books

hello PF, I want to know more about stellar evolution and about the end of the star's life. I want something that is not very superficial as i get bored when the content is not really deep. Thanks.
26. ### A The Speed and time relationship

Q.1 Will time for an object be slowed ONLY when it travels VERY NEAR TO the speed of light? Or should it be EXACTLY in speed of light?
27. ### How satisfying is working for NASA?

Its always been a dream of mine to work for NASA but so many people (whether they've worked for them or not), have said that it takes so long to work towards and it isn't even that satisfying of a job...
28. ### B How many points can be found in the surface of the Earth?

The other day I was wondering if as the universe is infinite and you can say that every single point in it is the centre of the universe, or that there is no centre for the same matter. Since you are not able to set up a centre in earth's surface. Is then earth's surface infinite? When you talk...
29. ### Find Internal Resistance From 2 Circuits w/ The Same Battery

Homework Statement A battery with an emf of 60 V and an internal resistance (r) is connected to a 10 ohm external resistance. The power lost inside the battery is 50w. The same battery is then connected to a 4.0 ohm resistance. The power loss is 200w. What is the internal resistance of the...
30. ### Is it possible to find refractive index from diffraction?

Homework Statement I am trying to find the refractive index nylon (fishing line) , however when I used a laser onto the fishing line (nylon) it looked like it diffracted. Homework Equations I am able to find the diffraction if that was what it was showing, however I dont know how to calculate...