1. ### How does the release angle of a catapult affect the object's velocity?

[Moderator: repeated text removed.]
2. ### Electric Fields and Electric forces help

Homework Statement This is the question Structure opposite comprises 5 ions each of which has lost one electron. The sides of the square formed by the 4 outer ions are of length 0.2nm Ion E is at the midpoint 1.What is the force on A due to ion A? Homework Equations I'd imagine: F= kq /...
3. ### Perturbation for Yukawa Potential

Homework Statement The photon is normally assumed to have zero rest mass. If the photon did have a tiny mass, this would alter the potential energy the electron feels in the hydrogen atom (due to the Coulomb interaction with the proton). The potential then becomes yukawa potential...
4. ### I want to Fetch Ideas for my School Project!!

Hello Forumers, Its been very long time since I haven't not been on PF. Today that streak ends!! I want ideas for my physics school project. please give me some great ideas & where to find it!!! please keep the following in mind while giving ideas:- 1. I am 12th Grade student 2. I want a...
5. ### Determining reaction of indeterminate beam structure

Homework Statement Homework Equations The Attempt at a Solution [/B] As this is an indeterminate structure with degree of redundancy 2, I have released support B & C. I then draw the BMD M0 of the Primary structure as well as BMD m1 and m2 of unit load system acting on B & C as follow...
6. J

Homework Statement An example in my problem set (homework help) An oak rod is hung from a rigid support. The rod has a diameter = 12 mm, length = 9 m, and a catch plate at its base. a) The maximum mass of a weight that each rod can support. b) The minimum mass of a weight that will break the...
7. A

### I Best equations to analyze using Big O

What would be interesting equations to work with, using Big O? I'm searching for something that may look simple at first, but can evolve into something more complex!
8. A

### Relationship between Launch Angle & Horizontal Distance

Homework Statement How to prove the correlation between launch angle (<45°) and horizontal displacement. Independent Variable: Horizontal distance Dependent Variable: Launch Angle (Important) Controlled Variable: Firing velocity [90 m/s] Another problem is, with the data that I have...
9. C

Homework Statement July 22,2017. Homework Statement Television and radio waves can reflect from nearby mountains or from airplanes. Such relfections can interfere with the direct signal from the station. a. Determine what kind of interference will occur when 75-MHz television signals arrive at...
10. ### Potential energy of rubber bands

<Mentor's note: moved from a general forum and therefore no template> This is the equation of potential energy in rubber bands, however, I don't know how to calculate the inertia of the arm of catapults or get the k constant. And what does n mean? Basically, i don't understand the whole...
11. ### Build a mousetrap racecar

Homework Statement For school, we have to build a mousetrap car, and get it to go 3m. Our car doesn't roll very well, and we aren't quite sure of the problem. We have an axle that is 5mm wide, and the thing that holds it to the chassis is made of cardboard. Also, the mousetrap is pretty far...
12. ### I Mousetrap race car is not working

Hello, so for school I'm building a mousetrap with my group for a project, but our car isn't moving. We filmed it snapping, and it doesn't seem like it is because of friction, since the axle spins pretty well. We thought that it was because the thing that holds the axle bends, but after fixing...
13. ### Parallel plate capacitor voltage question

Homework Statement A parallel-plate capacitor is connected to a 100 V battery until it is fully charged. The distance between the plates is d and the space between the plates is filled with air (k=1.0). Then, the battery is disconnected. If the distance between the plates is increased to 3d...
14. ### Help on pulley problem!

<Mentor's note: moved from a technical section, therefore no template> hey guys, i have a question about a tricky physics 1 problem our teacher gave us today, paraphrased as follows: there is a mass M1 on a flat, frictionless horizontal table connected to a pulley, and on the other side of the...
15. ### Investigate one factor that affects the angle of refraction

Statement: I need a suitable method and factor to investigate ONE factor that affects the angle of refraction. It has to be related to the context of everyday life and glasses, i.e. how glasses are used to focus light and the light focused is that of a refracted ray. Therefore factors such as...
16. ### 555 timer IC - Calculating resistance needed

Voltage = 9.0 V, Current = 20 mA, Capacitor (C) = 10 microF, Resistance before (too high) [R_A = R_B] = 10 k Ohms. In a a-stable oscillator, calculating the resistance needed for two resistors (R_A = R_B) to discharge and charge a capacitor (C) so that a LED does not blow. Currently my circuit...
17. ### Comp Sci Need to write a Python program, urgent

I really need help with a big Python program. Our professor has been MIA for the whole term and now we need to submit a program. I thought I was doing and learning fine on my own, but the program simply does not work for me. I need it till Thursday and I am ripping my hair out because I cannot...
18. ### Nuclear reactor reaction

Can someone please explain to me why the answer to the following question is Krypton? A step by step solution would be ideal please! (b)The following reaction occurs in a nuclear reactor: 235U+01n →141Ba+X+301n+202.5MeV (i) Identify the element X. Many thanks! (Question is Q12 b part i...
19. ### Selective precipitation, purity and yield of precipitate

Homework Statement An aqueous effluent contains 12 M Cd2+ and 10 M Mg2+ as solution of nitrates. Current practice is use NaOH to selectively precipitate the metals. (a) Is it feasible to get 0 Cd impurities in Mg ppt by using NaF instead of NaOH (back up your answer with adequate calculations)...
20. ### Finding the work done on a cutting tool

Homework Statement A cutting tool under microprocessor control has several forces acting on it. One force is F⃗ =−αxy2j^, a force in the negative y-direction whose magnitude depends on the position of the tool. The constant is α = 2.70N/m3 . Consider the displacement of the tool from the...
21. ### Heat equation problem so confusing

Homework Statement The problem is f(x) = sin2πx - (1/πsquare)*sinπx and its given Bn sin (nπx) = f(x) Question is find Bn. Homework Equations Bn = 2/L ∫ (sin2πx - (1/πsquare)*sinπx) * sin(nπx/L) where L is 1 The Attempt at a Solution I did [/B] ∫ sin2πx * sin (nπx) - (1/πsquare)*sin...
22. ### Integration Question

Homework Statement Using \int_{-\infty}^{\infty}e^{-x^2/2} dx = \sqrt{2\pi}, Integrate x^(5/2) e^(-x) dx from 0 to infinty 2. The attempt at a solution I tried substituting x = u^2/2 but i could not simplify further. Please help me with the problem. Thank you in advance.
23. ### A worker lifts a 20.0-kg bucket of concrete from the ground

Homework Statement A worker lifts a 20.0-kg bucket of concrete from the ground up to the top of a 20.0-m-tall building. The bucket is initially at rest, but is traveling at 4.0 m/s when it reaches the top of the building. What is the minimum amount of work that the worker did in lifting the...
24. ### What is the acceleration of the sled?

Homework Statement A sled starts from rest at the top of a hill and slides down without constant acceleration. At same later time, it is 80 ft. from the top ; 2s after that it is 125 ft. from the top ; another 2s it is 180ft from the top. a.) What is the acceleration of the sled? b.) how long...