# What is Physic: Definition and 221 Discussions

A physic garden is a type of herb garden with medicinal plants. Botanical gardens developed from them.

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1. ### Advice for self-studying biophysics after my BSc in Physics

TL;DR Summary: Briefly i'm asking for guidance through self-studying biophysics. Hello everyone, i've almost finished my bsc in physics and i got intrigued by biophysics, although my university doesn't provide courses for the subject. I wanted to get a grasp of the subject by myself but...
2. ### About semidirect product of Lie algebra

Homework Statement: About semidirect product of Lie algebra Relevant Equations: ##\mathfrak{s l}_2=## ##\mathbb{K} F \oplus \mathbb{K} H \oplus \mathbb{K} E## Hi, Please, I have a question about the module of special lie algebra: Let ##\mathbb{K}## be a field. Let the Lie algebra...
3. ### What Does $$E^2_k|_{k=k_{res}}$$ Mean?

Hi, just wondering what this thing means. $$E^2_k|_{k=k_{res}}$$ Just the k=k(res) after the vertical line. There is no definition in the textbook but in math does that mean from K=K(res) to something that can be dependent on a function or a situation? Like definite integrals answer...
4. ### Given a Constant Acceleration magnitude of g/4, Find the value of t

I got to the quadratic equation of the motion where: 4gt^(2) - g(delta t)t - g(delta t) = 0 and tried to solve for t. In this case, we would take the positive discriminate since we are dealing with the passing of time. t = ((sqrt(17) g(delta t)) + g (delta t)) / (8g) However, this is the...
5. ### How can I determine the shape of an oldie acid molecule?

I have done all of the questions apart from c and d. For a I got the answer 2.58*10^_5 cm^3 B) 3.72*10^-7 cm But for c I don’t really know how to start. I first thought of using the formula for volume of cuboid but don’t know how that’d give the answer for the dimension. For D, I turned the...
6. ### How do you know if the focal length is positive or negative?

In this problem, it doesn't tell you where is the focal length. So how do you know if it is in front or behind the object?
7. ### Confused about applying the Right Hand Rule (RHR)

the answer is attractive. but i don't see how this is how I draw mine and I use the RHR on the magnetic field between the two wire and I got the force is opposite
8. ### Studying Struggling to teach myself math and physics

Hey! I want to study physics and math, and eventually, I would like to get a Bachelor in Physics. I quit university about 5 -ish years ago, an Engineering major...I wasn't a good student and don't really remember anything. A couple of years ago I discovered a big interest in Physics and...
9. ### Help understanding "Heat capacity"

Homework Statement:: First of, this is not a "homework" per say, since this is not in my curriculum. If you still want to help, see the description :) Relevant Equations:: C = Q/(delta T), where delta T is the raise in temperature in Kelvin and Q is the added heat energy I want to learn about...
10. ### Find the acceleration in circular motion

Hello , First of all , I am still new to circular motion or any motions in general and still relatively learning so please bear with me. 1 . The direction of the tangential acceleration is parallel to the net velocity and that of radial of perpendicular to the velocity. So the direction of net...
11. ### I Why is my magnetic levitation experiment not working?

[Mentor Note -- Two similar thread starts merged into one] Hey all, I have been working on this project for a while now, which features suspending an object midair through the use of magnetic levitation principles. Cool right? And so I have been researching and trying, even finding ground...
12. ### Quick question about which radius to use on Gauss' law problem

confused on part A/B when I look up they did E= Q/2e(0.8)^2. But why not use the 0.100mm because that is the area of the enclosed. Same with B why did they use 100m and not 0.8m because 0.8 is smaller so it enclosed the charge
13. ### Electric field / Gauss' Law --

Electric Flux = E*A = 5*6(0.05)^2. when i look up at other sources they use Electric flux = q/ (8.854*10^-12 [this is e]) equation but I am confused on why the E*A equation don't work. The answer is 0.02Nm^2/C
14. ### Engineering Acceleration Engineering First Semester

The function x (t) = 4 (m · s) t − 1 + 10 m describes the position of a mass point. In which direction does the speed point at time t = 1 s? Is the amount of speed constant or not? does the velocity function change its sign for t> 0 at some point? And in which direction does the acceleration...
15. ### Thermodynamics: Ideal gas model

Do particles have air in between them in the ideal gas model? I think the answer is 'no, but I am not quite sure about the explanation. Is it because in an ideal gas model, the volume of the particles is negligible? Thank you.
16. ### What velocity does the particle need to get to point B?

It was a long time ago I did these kind of problems so I’m a bit rusty. The only thing I can think of is divide it up to two parts one x and one y. In y the acceleration is sin(a)*9.82? Then put that in the equation and solve for t. In x the there is no acceleration so the formula is x=V0*t, I...
17. ### How far can the person climb up the ladder before it starts sliding?

Look on picture two for my equations, I’m pretty sure my first three equations are correct as it’s the same on the answer paper I got. Answer paper only shows the three equations and correct answer so I have no idea how they got to it. When I put the equations togheter And solve out ”h” i get...
18. ### What is the resulting force between the beam CB and E?

I assumed that the vertical force at point B would be the same as the force between beam CB and E because of Newtons law. Did I assume wrong? Look below for my calculations and answer which I got to 250N. I don’t know the correct answer but assume someone here can tell me if I solved the problem...
19. ### B Does a rubber mat on a device prevent static build up

Does a rubber mat on a device prevent static build up and discharge on a metal device well using it
20. ### What other information is needed to solve this equation involving b?

the equation is not equal not to anything (example: 3x = 6) and i don't know how to resolve [e ^ - (b / 2m) t].
21. ### I The solar system and the Coriolis effect

After concluding an investigation about the coriolis effect, I wondered how this phenomenon affected the solar system and in particular the moon. Since the moon is a body that moves within the rotating system formed by the sun and the earth, an apparent deviation in the moon's path would be...
22. B

### Is PF the Ultimate Physics Forum?

I found PF on internet when I search for physics forum
23. ### Α baseball player throws the ball....

Hi all ! I wonder if I'm right. (From : Fundamental University Physics, Volume 1 (Mechanics) - (Marcelo Alonso, Edward J.finn) Addison Wesley 1967) This is my try: * I have the Greek version of the book and there is no answer.Thanks.
24. ### Which of these methods of propulsion is “best” for future spaceflight?

Summary: Which of these hypothetical propulsion methods is the best for a spacecraft during Interplanetary flight? Let’s just assume all at this point are cost-effective at the time. Consider the •Safety of the engine •The speed •The efficiency 1.) Monoatomic hydrogen propulsion 2.)...
25. ### Calculating the coefficient of friction Given 2 forces and and angle

i tryed putting all the number into that equation but it does not work, i have no clue if i need to include the angle to solve this or not and if i do i have no clue how i would
26. ### How can I calculate the rate of energy absorption from nuclear decay?

Problem Statement: Started with a 0.1g of cesium-137, decayed into ba-137 after twelve hours by beta decay, this starts to decay with gamma rays. 12 hours after this someone pockets the sample and absorbs 50% of the beta particles and 10% of the gamma rays. How would I find the rate at which...
27. ### Vectors Homework Help: Find Degree

Can’t seems to find the degree
28. ### Why is the x-component of the electric field at point P positive?

I got the answer: E(P)=(k*Q)/(3î )−(k*Q*ĵ) /2 Can someone confirm if this is the right answer?
29. ### I Understanding q: Lambda & S in the Equation

What is this formula? q=λ⋅S⋅∪_x What does s and lambda mean?
30. ### Law of conservation of angular momentum

Given the figure, how can i arrive to this formula knowing that angular momentum is conserved? I know that p = mv and L = p x r. So the initial momentum will be L1 = mV x R and the final momentum will be L2 = mv x r. I am not sure how R will equal to b since the distance between the...
31. ### MHB Understanding Unit Cancellation in Physics Equations

here's the question: a = b/e b = 1 kg m-1 e = 1 kg m-2 what is a? including units I assume it's to do with cancelling out the units when you divide but I really don't know what the answer is
32. ### Temperature Measurement: Are All Thermometers Created Equal?

What is the difference in temperature with different thermometers for the same object? Thanks !
33. ### Definition of work done by torque

I' m trying to derive the work done by a torque from W = ∫ F ⋅ ds and I' ve looked up the internet, it said: W = ∫ F ⋅ ds ( since ds = dθ × r ) ---------------------------------------- ( Line 1 ) it can be written as W = ∫ F ⋅ dθ x r this is a vector triple product , thus can also...
34. ### Short conceptual question on Work, Energy and Forces

Homework Statement (Please check the attached image) 2. Homework Equations The Attempt at a Solution Those are my answers. I thought the magnitude of the applied force would be bigger because that would be responsible of keeping the block on that spot without having it pulled back by the...
35. ### Calculate the mass when not hanging it in dynamometer

Homework Statement Hello! I have a physics problem that I can't solve. I'm supposed to describe how I can calculate the mass when knowing the µv (I don't know the english term but I'm guessing friction...something (friction when the object is not moving)). You are allowed to use a dynamometer...
36. ### Teaching high school students for the first time

Hello,I have been accepted for a physics teacher position in a high school. This would be my first job ever. I taught "tutored" students before in my home university for two semesters, and I think I am a good teacher. But, I feel that teaching high school students is totally different. I am not...
37. ### Physic (kinematics) — Displacement of an accelerating car

Question: A car accelerates from rest at a rate of 2.0m/s^2 [N]. What is the displacement of the car at t=15s? I tried (2m/s^2 [N])(15s)=30m/s [N] (30m/s [N])(15s) =450m [N] but guess wrong :( *Because the answer is 230m [N] How to solve this? anyone
38. ### A Subtract Radiated from Background Spectrum to Analyze Absorption Spectrum

Hi everyone, I have an absorption spectrum that I obtained from a sample after radiation and I need to use the background sample as a reference, how can I do that using excel? what I did is subtract the radiated from the background spectrum then plot it, is that right? Thanks.
39. ### Find the minimum distance between 2 particles

Homework Statement A point particle of mass m and charge q(>0) approaches to a point particle Q(>0) at a fixed position. When the distance between the two particles is L, the speed of the moving particle is v. The permittivity of the vacuum is denoted as Epsilon0. Find the minimum distance...
40. ### Can the only reaction force (to gravity) be friction?

Homework Statement If you have an object say in a vertical pipe, which only has a gravitational force acting on it would the reaction forces only be friction forces? If this is the case how would you calculate the forces? would you calculate the friction force using the friction coefficient or...
41. ### Does the angle of a beam fixed at two points affect the method?

Homework Statement if a beam fixed at two points is on an angle say 45 degrees from the x or y-axis instead of running parallel to x-axis in most questions does this effect calculations? The force acting upon it would be a load directly downwardsHomework Equations N/A The Attempt at a Solution...
42. ### Solving 2D FEM Error with Maxwell Version 17

Hi, I am working on Maxwell version 17. I have a simple motor to analysis 2D FEM. However, when I analyze the model, I see this error. "Maxwell2d solver, process solver2d error: Internal Solver Error: 'Transient solver handles only isotropic conductivity!'. (7:07:10 PM Apr 16, 2018)" I am...
43. ### Programs Physic undergrad and material minor?

Okay there's a lot to chow down here but I am at a standstill. Ultimately there are too many variables and unknowns but I need a framework. I am transferring over to ASU from a community college and have declared physics as my major. This is something I have planned on for a while because I am...
44. ### Other Can a physicist study evolutionary biology? How can I do?

Hello, I’m an undergraduate physics student. Recently, I recognize that I am interested in evolution and I want to study life’s origin. When I preferred physics, because I want to learn how nature works. Now, I am not only interested in how nature works, also I’m passionate for neuroscience and...
45. ### Understanding Bernoulli's Principle

My understanding of Bernoulli's Principle is something like this: Pressure is inversely proportional to velocity. Fluid flowing through smaller cross-sectional area has increase velocity & decrease in pressure. Also P = F/A... so would force also decrease for fluid going through small area...
46. ### What is the Significance of the Electric field in a closed circuit

Hi, I am confused about the electric field lines which are depicted mostly on the Internet as per conventional way. What I understand that the conventional current was due to positive charges which was wrong. Actual flow of the current was due to the negative charges or electrons. When the...
47. ### Find the current induced in a wire loop by a nearby current

Homework Statement Homework EquationsThe Attempt at a Solution When the circuit moves creates magnetic force that moves the some charges in the wire and that is a current. That is what i thought. F = Q.v B sin theta B = ( permeability Of vacuum* I)/(2pi.r) But how to find the I? Thank you...
48. ### Question about vacuum powered projectiles

I'm writing a novel and wanted to research a possible weapon I came up with to make sure the physics are at least possible. However, I could not find anything on vacuum-based projectiles other than ping-pong balls, while this is interesting, but it doesn't answer my question on what would happen...
49. ### Physics help to measure friction

<Moderator's note: Moved from a technical forum and thus no template.> Here’s the question Design a simple expirament that you could carry out in your own home to i) determine coefficient of friction between your object and surface ii) prove that coefficient of static friction is only...
50. C

### Understanding Rotational Velocity and Its Significance in Physics

As a student taking my first step into rotational physics in a classroom filled with students who have a year of this ahead of me I beg for help! :P So what is Rotational velocity? What does it define? How do signs work with rotation? What does its acceleration mean? Angular Velocity is...