# What is Introductory physics: Definition and 111 Discussions

The following outline is provided as an overview of and topical guide to physics:
Physics – natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.

View More On Wikipedia.org
1. ### What is ##Tds## in this equation : ##dU = Tds - PdV##

More explanation : First law is given by ##dU=dQ+dW##. For a reversible change we have: ##dQ = Tds## ##dW = - PdV## So I rewrite first law as : ##dU=Tds - PdV## As mentioned before this ##Tds ## is the heat transferred in a reversible change. And the ##-PdV## is the work done by system in a...
2. ### Graphically determining the focal length of a converging lens

So I have plotted all the given data points on a graph, putting 1/di on the y- axis and 1/do on the x-axis. I have to now find focal length from the graph? I'm not sure how, I'm thinking I have to rearrange the equation 1/f = 1/do + 1/di into y = mx + b form then go from there, but I'm totally...
3. ### Equilibrium of Forces and Torques on Sawhorses Supporting a Person on a Board

centre of mass of board at the centre of the board = at distance 6m from left end At no rotation condition and equillibsium IM= net moment of. force = 0 If, = net horizontal force =- ity = net vestical force =0 a. To prevent the board from rotating, the total torque on one side of the pivot...
4. ### Introductory physics: Time for a ball thrown vertically to reach maximum height

Is the answer key wrong? I keep getting the same answer and it is verified with the freefall equation distance=1/2 (g)(t^2)
5. ### Converting MeV/c^2 to kg

(1672 MeV/c^2) * c^2 = 1.505 * 10^20 MeV = 1.505 * 10^26 eV = 2.41 * 10^7 J Since E = mc^2, m = E/c^2 Therefore, m = 2.41 * 10^7 / (3 * 10^8)^2 = 2.68 * 10^-10 kg But the answer is 2.97 * 10^-27 kg Help! What is wrong with my logic?
6. ### Rotational problem of arm - wrestling

For number 6 I answer (a) and for number 7 I answer (d) but I can say I just take a guess. In question 6, I tried to think about Newton 3rd law. The force exerted by each arm on the other is equal so assuming the distance from the point where the force acts to the pivot is also the same, the...
7. ### Fluids: Concept about Fluid Pressure in a relation with Force and Area

I've already got the correct answer in letter (a), which is 17140.2 Pascals. My question will be focusing about the letter b of the question and here is my solution: (b) FORMULA: P = F/A F = P*A My understanding about this problem is I have to use the pressure that I got in letter (a) to...
8. ### Force between 2 point charges in VECTOR format (x i + y j + z k)

I tried using the distance between r2 and r1 and plugging them into the equation for i, j, k. >> So for the force in the x direction it was k*(4E-6*4E-6)/(4-9)^2. The answer I got was wrong according to webassign. Can someone please tell me what I am missing?
9. ### Problem involving Torque and a Derrick from Feynman Exercises

I attempted to solve this problem by considering the torque caused by the perpendicular components of the tension and weight with respect to the derrick. $$Tcos\theta x = Wsin\theta L$$ $$T = \frac L x Wtan\theta$$ Using the principle of virtual work I also arrived at the same answer by...
10. ### Intro Physics Recommendations on Introductory physics and AP physics 1 books?

Greetings to all. I'm looking for the best textbook for introductory physics that has clear explanations and is problem-oriented. I'd also appreciate any recommendations for textbooks for the AP Physics 1 exam.
11. ### Calculate the best angle for maximum light dispersion through a medium

I first thought that the angle would have to be maximum when it is closest to the critical angle for total internal reflection. From my lectures the equation for the critical angle is ##\theta _1>\ sin ^{-1} \left( \frac {n_2} {n_1} \right),## so as ##n_2 = 1##, we have ##\theta _1=\sin...
12. ### Intro Physics Introductory Physics, by John D. Mays

I understand the reaction from the majority of those here in PF to John's reference to his faith in this book: however, if you set aside all such references for the moment and just look at the way Physics is presented in the book how would you who have read it rate it on a scale of 1 to 10 for...
13. ### Entropy Change & Heat Transferred to a Gas

By using the given relationship that S=a/T --(1) along with the equation ∫ (delta Q rev)/T=∫dS -- (2) I found out that my answer for the value of Q is mc*ln (T2/T1)*a upon equating (1) & (2). But the solution is instead given as Q=a*ln*(T1/T2). I would be grateful if someone would point out...
14. ### Question on RMS Mean Free Path

lambda (rms)= v(rms) * t(rms) -- 1 Now I assume here that t(rms)=1/(√2*n*π*d^2*v(rms)) But this cancels the v(rms) term when used in eq (1) so the mean free path and the RMS free path would actually be the same (even later on when used in the aforementioned Survival Equation) I would like to...
15. ### To find total work done from multiple reversible processes

The question is given in 3 parts. For first part, process is isochoric so Work done=0. We know here that at end of the process (a), T2=T1 while V remains constant (we can take it as V1) so P2=2P1. For second part, process is isothermal so T is constant. At end of process we reach P1 again from...
16. ### Work & Energy (Question on Classical Mechanics/Slope based Problems)

I used the Change in Kinetic Energy and equated that with the Work Done. The "Work Done" part comprises of two different functions- one is work done by Gravitational Force while the other is the work done by frictional force (or the brakes). /Delta KE (magnitude wise)= 0.5*1350* (20^2)=270,000...
17. ### Maxwell's Distribution Law (Thermal Physics)

There are two questions in the photo. I have attempted the solution (attached below) and I would be highly obliged if someone would verify the same. Edit- Sorry the images of the solution have uploaded in the wrong order. 5th and 1st Image comprise of both parts of Q1 while the remaining of Q2.
18. ### Question on First Law of Thermodynamics (Paramagnet)

For the first part, I have expressed it in the following differential form- dU= delta (Q) + BdM Now for the second part I am having major confusion. I know that B corresponds to P and M corresponds to V as generalised force and generalised displacement respectively for a Paramagnetic substance...
19. ### Intro Physics Introductory physics books?

Are there any books that are NOT like "University Physics (Young)" / "Fundamentals of Physics (Halliday)" in presentation, but that are suitable for a first course on the subjects of those books? The mentioned books are too "flashy", full of colorful boxes, etc. I don't like this and I find it...
20. ### I Fluids: Bernoulli's Equation Derivation Question

I figure that either the Force F2 is applied in the opposite direction because of some kind of resistance, but I'm not sure. Thanks!
21. ### Intro Physics General introductory physics books compared to specific books on each topic

What exactly is the difference in the way an general physics book (Halliday and Resnick, Young and Freedman) covers topics like mechanics, EM, and thermodynamics, compared to respective books like Kleppner and Kolenkow, Griffiths, and Schroeder, other than the amount of material covered for each...
22. ### I Gap between introductory physics & solid state physics?

The left pic is the initial state and the right pics are 2 different descriptions for a metal under electric field E. Are the 2 on the right contradictory and which is correct?
23. ### A Graph analysis problem to find when the acceleration is zero

I had deduced that B,E,H are the places where acceleration will be zero, but when I read the solutions it showed that K also has a = 0. It said it had maximum slope and then said a = 0. But I couldn't understand why? Please help.
24. ### Using Impulse to Solve For the Final Velocity

Hi there, Just asking a logistics question since I want to be sure I am approaching this problem correctly. My professor showed me an example of a bullet being fired from a barrel, given its initial velocity was 0. The change in time was 0.1 seconds. The mass of the bullet is 0.02 kg. The...
25. ### Magnetic field on a loop due to another loop

In the attached picture, the outer wire is carrying a current I(t), and it's asked to find the induced EMF in the inner loop. Now I have indeed calculated the B-field along the z-axis due to the outer loop. My lecturer then puts z=0 into that expression and then multiplied it with the area of...
26. ### Universal Gas Equation problem

Hi everyone, I'd really appreciate any help with this problem: A helium cylinder for the inflation of party balloons hold s 25.0L of gas and is filled to a pressure of 16500kPa at 15 degrees celsius. How many balloons can be inflated from a single cylinder at 30 degrees celsius if the volume of...
27. ### Studying What books are good to learn the math in intro physics?

I'm struggling with the math used in my college's calc-based honors physics class, even though I've taken calculus 1. ---What are some good books/resources to learn the math used in introductory physics?--- Preferably, it'd be nice if the math was taught using examples in physics. Having that...
28. ### Courses Is it okay to not understand the calculus in intro physics?

I don't understand a good portion of the non-algebraic math behind much of the physics in my first semester college class. I understand everything with algebra, and can solve all problems, but I don't understand the relationships with vector cross/dot products, calculus derivations, DE, etc...
29. ### Studying Conceptual Deficits in my Introductory Physics course

Hello! I'm enrolled in PHY 1 in college and this is my first encounter with the subject. I'm usually able to derive the correct answers to the questions, but I consistently sense that I lack a firm understanding of what I'm calculating and or the justification of the steps involved. That...
30. ### Introductory Physics - Finding "little g"

Hello i am new, I have written this piece for homework with reference, and wondering how i can write it better. Maybe i have written too much or too little, i would appreciate some help. Regards. Little gLittle g, what is considered as G-Force or Gravitational Force is the force in which...
31. ### What angle will give the object the greatest range?

Homework Statement 1-A rifle can shoot a projectile with a velocity of 207m/s. At what angle should the rifle be pointed to give the maximum range? 2-Evaluate the maximum range Homework Equations N/A The Attempt at a Solution I considered at first that the problem seemed like it could be...
32. ### Struggling with a free-fall question

Homework Statement Two stones are thrown simultaneously, one straight upward from the base of a cliff and the other straight downward from the top of the cliff. The height of the cliff is 6.00m. The stones are thrown with the same speed of 9.0m/s. Find the location (above the base of the cliff)...
33. ### Database of physics powerpoint slides?

Is there any website that has a database of physics (or other course) powerpoint slide sets? For example, I am teaching both an introductory physics class, and a separate calc-based physics class of what should be the same general material as the non-calc-based. For the former class I am using...
34. ### An equilateral triangle's electric field at its center

Homework Statement Three 18-cm long rods form an equilateral triangle. Two of the rods are charged to +10 nC, and the third to - 10 nC. What is the electric field strength at the center of the triangle? Homework Equations $$\vec{E} = \frac{k*q}{r^2}$$ The Attempt at a Solution 1. Draw...
35. ### Angular momentum and rotational energy

Homework Statement A school playground has a carousel, which is simply a circular platform that can rotate around its center axis with negligible friction. This carousel has radius r=1.6 m and rotational inertia I= 177m^2kg. Suppose you are standing beside the carousel which is already spinning...
36. ### Scuba Diver Sees Bird: Refraction Problem Explained

1. The problem statement, all variables, and given/known data A scuba diver is underwater. She looks up and sees a bird flying in the sky. Compared to its actual distance, the bird appears to be... 1. Closer 2. At actual distance 3. Further Homework Equations n1sin(θ1)=n2sin(θ2) The Attempt at...
37. ### General Definition of Potential Energy - Conceptual Help

My textbook states that an alternative definition of the change in potential energy is the work required of an external force to move an object without acceleration between two points. I am confused on why it says acceleration. Wouldn't that mean that the acceleration is 0 and therefore the...
38. ### Engine Efficiency: Find ΔW & ΔQh

Homework Statement An ideal gas with Cv = 5 2R, and γ = 1.4 starts at a volume of 1.5m3 , a pressure of 2.0×105Pa ,and a temperature of 300K. It undergoes an isobaric expansion until the volume is V , then undergoes an adiabatic expansion until the volume is 6.0m3 , and finally undergoes an...
39. ### Ideal Gas Law -- Isobaric Epansion followed by....

Homework Statement An ideal gas with Cv = 5/2R, and γ = 1.4 starts at a volume of 1.5m3 , a pressure of 2.0×105Pa, and a temperature of 300K. It undergoes an isobaric expansion until the volume is V , then undergoes an adiabatic expansion until the volume is 6.0m3 , and finally undergoes an...
40. ### Carnot Cycle: Analysis of Energy Exchange

A refrigerator operates on a Carnot cycle. In this cycles, it absorbs 120 J of energy at a temperature Tc while 300 J of work is done on the gas undergoing the cycle. How much energy is exhausted as heat during this process? The answer is 420 J. I am unsure of where to start for this...
41. ### How to solve this pendulum problem?

Homework Statement For number 3,4,5 https://s4.postimg.org/qbp3xzq65/IMG_1092.png https://s22.postimg.org/u220j60sx/IMG_1093.pngHomework Equations Centripetal force = m v^2/R T = centripetal force + w Sigma F = m.a The Attempt at a Solution Number 3. Find the v at D point using...
42. ### Intro Physics Introductory physics textbook for a math student

Let's start off by assuming that I know no physics at all. I am looking for an introductory physics book that is mathematically rigorous, but doesn't let formalism and rigor get in the way of intuition. My goal is to start from the "beginning" of physics and eventually reach general relativity...
43. ### Careers that use introductory physics concepts

I have an assignment on researching 2 careers that use one of the units of Physics that we've studied this year. The units we studied were Forces and motion (kinematics), Energy and Momentum, Electric and Magnetic fields, and Waves of light (not too keen on doing it for this.) I have to give a...
44. ### Solve Torque on Cylinder Homework Problem

Homework Statement A cylinder having a mass of 5.0 kg can rotate about its central axis through point O. Forces are applied as shown in the figure: F1 = 5.0 N, F2 = 6.0 N, F3 = 2.5 N, and F4 = 5.5 N. Also, R1 = 6.5 cm and R2 = 12.0 cm. Find the magnitude and direction of the angular...
45. ### A falling stone takes 0.28 s to travel past a window 2.2 m...

Homework Statement A falling stone takes 0.28 s to travel past a window 2.2 m tall. From what height above the top of the window did the stone fall? So from this problem I think I have these variables: vo = ? (or 0 because falling usually indicates 0 for an initial velocity?) yo = 0 y = 2.2m...
46. ### How would you find Va and Vb in the problem below?

Hi I am new the site and have to complete this physics summer work from a not so clear textbook. I am also new to a lot of the concepts and material. I was unsure on how i go about solving velocity a and b in this problem: any help is appreciated
47. ### Schools AP Physics C and College Introductory Physics

Hi everyone, I want to know that if a five on Ap Physics C exam can replace college's two introductory physics courses. Also, what topic should I study after Physics C that helps me to be better off in college higher-level physics? Thank you.
48. ### Dimensional Analysis Pendulum Equation

Homework Statement The period of a simple pendulum, defined as the time necessary for one complete oscillation, is measured in time units and is given by T = 2π ℓ/g where ℓ is the length of the pendulum and g is the acceleration due to gravity, in units of length divided by time squared. Show...
49. ### Intro Physics Which book to read the summer before starting Physics?

I'm starting my 1st year of Physics at university in September. Although I've learned a lot of single variable Calculus and various topics of Physics this year, I'd like to get a general overview of the topics touched in a 1st Physics course at uni. I just wonder if there's an equivalent to...
50. ### Curves on a Position time graph

Homework Statement Homework EquationsThe Attempt at a Solution I knew the answer was between A and B, but the inward curves and outward curves on the position time graph confused me , what exactly does it mean? -does A have an increasing velocity and then B has a decreasing velocity? I am...