Mechanic Definition and 124 Threads

  1. S

    Potential Energy vs. Position Graphs

    Homework Statement A particle has the potential energy shown in the figure. (Figure 1) What is the x-component of the force on the particle at x =5, 15, 25, and 35 cm? I'm stuck on finding the Fx at 25 & 35 cm.Homework Equations F = -du/dx 100 N = 1J/cm The Attempt at a Solution Slope...
  2. mamadou

    I How do we compute an integral with a dot product inside ?

    I was trying to solve a problem involving work , as we know : w = \int_{a}^{b} \vec{f}.d\vec{s} but in my problem the path was cyrcular , so how to evaluate this kind of integral ?
  3. Fasso

    I Probability of Particle Collision on a Closed Surface

    Is it more probable that particles will collide if both are moving or if one has velocity equal to 0? Let's say we don't have any forces between them and they're on a closed surface (for example a square).
  4. A

    Need help with Mechanic Energy math problem.

    Homework Statement "A little girl is sliding down a snowy hill on her sledge and out on a horizontall flat area. The girl has a physics interested mom which wants to know what the maxium speed the sledge can reach. She measures that the hill is 3,0m high and 6,0m long. The sledge slides for...
  5. P

    Very quick easy Trig/Angle question

    Homework Statement The river flows 5km/hr in the west direction. The boat that has a speed of 10km/hr. It starts from the south bank to the north. Then the question is to essentially find the angle theta. Homework Equations Tan-1(5/10) or Tan-1(10/5)The Attempt at a Solution Tan^-1(5/10) or...
  6. V

    How Do Tension and Friction Forces Interact in a Two-Block System?

    Homework Statement 2 Blocks connected by a string is placed on a rough horizontal floor,the coefficient of friction for block 1 is 0.2 while for block 2,it is 0.1. A force of 8N is applied on block 1 and a force of 1N is applied on block 2.Find the tension in the string and the frictional...
  7. TheQuietOne

    Where Can You Find Custom Jumpsuits Online?

    I seem to have looked everywhere but can't find a good website. is there a place I can get custom jumpsuits? all I get are star trek shirts. :oldconfused:
  8. E

    Understanding Newton's Third Law: Exploring Confusion and Misconceptions

    I am not the best at drawing, I know. If A exerts a force of 200N on B, then by Newton's third law, 200N would be exerted on it. Similarly, if B exerts 100N on A, by Newton's third law, 100N would be exerted on it. Then why wouldn't both accelerate in opposite directions with accelerations equal...
  9. Nader AbdlGhani

    Calculating Distance Covered by a Particle Using Displacement Vector

    Homework Statement The displacement vector of a particle of mass 50 gm. is given as a function in time (t) by the relation ##\vec S##=(5t-t2) ##\hat c## where ##\hat c## is a constant unit vector , s is measured in centimetre and t in second .Knowing that the particle started its motion at t=0...
  10. Gbox

    Graph displacement as function of time

    Homework Statement let there be ##\beta(t+\tau)^{-2}e^{-3}cos(at^{3})## where ##\beta##, ##\tau## and ##a## are constants Homework Equations ##\beta(t+\tau)^{-2}e^{-3}cos(at^{3})## The Attempt at a Solution I know the graph is going up and down exponential but how can I draw it more...
  11. FruitNinja

    Time it takes for block to slide down an incline in elevator

    Homework Statement MECHANICS: Given Theta, L, M, and acceleration of elevator relative to ground. Find the time it takes for the block to reach the end of the incline. Here is a diagram: http://k-elahian.com/tmp/nip.PNG Homework Equations f=ma kinematics relative acceleration The Attempt...
  12. Elena14

    Find Centre of Mass of a Metal Sheet

    A thin sheet of metal of uniform thickness is cut into the shape bounded by the line x=a, y=kx^2 and y=-kx^2 . Find coordinates of center of mass. My attempt at the solution : To apply the formula r(c.m) = (Σm1a1)/Σa1 ; a is the area; we need to know the area but we have just been given the...
  13. A

    Motion of parallel-incoming particles in gravitational field

    Question: There is a large parallel beam of incoming particles with mass m and uniform velocity v0 (v0≪c) in the presence of a gravitational field of a (spherical) planet with mass M and radius R. (without GR) The question is what fraction of the particles will eventually arrive at the planet...
  14. G

    A spring is suspended on the ceiling of a truck, find acceleration?

    Homework Statement A massless spring with a spring constant k = 500 N/m is suspended from a hook on the ceiling of a cargo truck moving in a straight line (horizontally) on the highway. A child reaches over from her seat and suspends a 1.1 kg toy on the free end of the spring. The child...
  15. A

    Unsure of mechanics problem, circular door on hinge...

    1. In the attached imjage, the centre of gravity of an open door acts at G equal to 255N; a) Determine the x,y,z, components of reaction at the hinge A in equilibrium b) Determine the force along CB Little stuck with this problem, obviously this falls under resolving forces. I assumed Az,Ay = 0...
  16. jeremyskate

    Calculating velocity and position from time variating force

    Homework Statement 2. Homework Equations [/B] v(t)=∫a(t)dt r(t)=∫v(t)dt The Attempt at a Solution f=ma a(t)=f/m a(t)=(4/5t^2i-3/5tj) (integrate) v(t)=4/5i(t^3/3+c1)-3/5j(t^2/2+c2) how can i get rid of the c1 c2?
  17. M

    How to Perform Classical Mechanic Transformations?

    Hello everyone, I have a little problem with some transformation. I wonder how i can get that result. Can somebody explain it step by step? The " ' " means derivative. Thank you for your time ;)
  18. K

    What's the greatest mechanical force we can achieve?

    hello everybody, just doing some general designing and was wondering what is the greatest mechanical force we can achieve already, in the form of a piston or a press. i am not to sure how, just want to know the value and how its achieved.
  19. L

    Maximum Angle for 2D Collision: Does θmax Exist if m1 > m2?

    Homework Statement A mass m1, with initial velocity u, collides elastically with mass m2, which is initially at rest. After collision, m1 deflects by angle θ. Find the maximum value of θ. The answer given is θmax=acos(sqrt(1-(m1/m2)^2)). Does this mean that the maximum angle cannot exist if...
  20. B

    Engineering Can mechanic engineer technician become an machanic engineer

    Right now, I'm working as a water jet and plasma cutter operator. I want to go back to college to get a degree on the upcoming semester I'm deciding to enroll one of these program 1.Mechanical Engineering Technician - Industrial 2.Mechanical Technician - CAD/CAM - Fast Track follow by...
  21. M

    Why is torque perpendicular to the force applied?

    I understand the right hand rule and the equition, but why is the direction of the torque perpendicular to the force on the counter clockwise side of the force and crossing the rotational point?
  22. loreberto911

    Analytic mechanic, disk and rod

    < Mentor Note -- thread moved to HH from the technical engineering forums, so no HH Template is shown > A rod rolls without creep. And the disk rolls without creep on Q. The rod can just moves on y. Which is the relation among Va and Vohm? Va= velocity in A My resolution: in Q we know that...
  23. U

    Hydrostatics on plane surface (basic fluid mechanic Q)

    I don't understand how they got the "position of individual forces". For F1, I'm guessing they used a pressure diagram and that's why it's 2/3 from the tip of the triangle. But why wouldn't the force act on the centroid for this square section (thus its 3.5/2)? But for position of F2 (y2)...
  24. T

    Torque, Angular Momentum, and Conservation of Mass Problems

    Homework Statement I am studying the topics listed above and have been having great difficulty getting my problems going. To explain, I am having difficulty seeing where the problem should go and attacking in that direction. I can draw out free-body diagrams but I can't see how to solve the...
  25. OenoLovesPie

    Classical Classical Mechanic books for a Secondary Student

    I am a secondary student who is in grade 10, which means that I am only beginning to learn physics and calculus (e.g. Newton's Laws and Binomial Theorem). I have a passion for physics and has been getting relatively good grades but recently I started to lay my hands on Newton's Laws and I am...
  26. T

    Quantum vs. Classical Mechanic graphing

    Hey, I am curious if there's a correspondence between Classical and Quantum Mechanics graphs in terms of Potential (or kinetic) Energy as a function of x, aside from equations?
  27. A

    HVAC /generator service mechanic should I pursue an electrical or mech

    I have been doing HVAC for 15 years and generators for the last 3. I'm 37 and will be working full time as I go to school. I'm wondering though where I should focus my major yet I do have lots of time. Since I'm only taking 2 classes this semester to get my feet wet. An English writing class and...
  28. L

    Effect of Additional 1/r^2 Potential Energy on Elliptical Motion

    Homework Statement Hi, this is one the problem on my homework, but I don't know where t start with this problem. We have equation of a particle's potential energy field: U(r)=-GMm/r+Cm/r^2 C is just a constant. I need to solve for its radial motion and angular motion, then if the motion of...
  29. S

    Fluid Mechanic Dynamic Similarity Question

    1. Hi All I had a quiz in my fluid mechanics class with the question A ship model scale 1/25 is towed through seawater at a speed of 1m/s. A force of 2N is required to tow the model. Find the speed of the ship if the prototype is subjected to wave resistance only. 2. REm=REp...
  30. A

    A few questions on quantum mechanic and photoelectric effects

    Hi all, I have a total of 6 questions, 3 of them are posted here and 3 of them are provided in the link because they involve graphs. 1. KE of an electron is twice that of a proton, what is ratio of de broglie wavelength of proton:electron? My answer: since de broglie wavelength is lamba =...
  31. A

    Fluid Mechanic - Pressure in the pipe

    What should I consider if I have three centrifugal pumps then the water of these three pumps flow into one pipe? How to calculate the pressure in the intersection of the three pipes?Thank You.
  32. M

    Quantam Mechanic - Particle in a rigid one-d box (PDF)

    Homework Statement Write down and sketch the probability distribution for the second excited state (n=3) of a particle in a rigid box of length a. What are the probabilities of finding a particle in the intervals [0.50a, 0.51a] and [0.75a, 0.76a]? Homework Equations |ψ(x)|^2 =...
  33. D

    Where to Begin with Classical Mechanics Problems?

    http://img27.imageshack.us/img27/1158/physich.png I really do not see how I can solve the problems. All I need is hint how to start the problems most of the time. I know I should read more, ask questions to teacher, etc. I have 5 classes, 5 homeworks to do every week. On top of that I have...
  34. S

    Mechanic about wood block, friction and pulley

    Homework Statement Two objects A and B weighing 50 N and 80 N respectively were connected by a light string over a fixed pulley. A was put on a reasonably long and horizontal table surface. The coefficient of sliding friction between A and the table surface is μ = 0.3 while the friction...
  35. sgtusmc

    Turbofan fluid mechanic and thermodynamic calculations

    I have recently developed a multi-computer networked simulation of a turbofan jet engine test cell control room, including a real-time simulated jet engine "model", PLC control logic, video playback of a engine at various states, and a throttle for maneuvering. I currently calculate all...
  36. bayan

    Quantum Mechanic. penetration distance and probability Density

    Homework Statement Assume that a typical electron in a piece of metallic sodium has energy - E_{0} compared to a free electron, where E_{0} is the 2.7 eV work function of sodium. At what distance beyond the surface of the metal is the electron's probability density 20% of its value at the...
  37. R

    Pressure problem(Fluid mechanic)

    1. Homework Statement enclosed, thanks for checking 2. Homework Equations P = ρgh 3. The Attempt at a Solution I have try to add up all pressure in the tank (including gauge pressure, pressure of the oil(ρg*0.5), pressure of the water(ρg*0.8)) but still can't balance out the...
  38. F

    Calculating Tension in a Horizontal Bar Connecting Two Halves of a Ladder

    Mass of man is = 80KG Mass of the ladder is = 20 KG Mass of the bar connecting the two halves of the ladder is negligible. The friction force between floor and ladders are negligible. (floor is frictionless) Question: find the tension in the horizontal bar connecting the two halves of...
  39. F

    Mechanical Problem: Calculating Car Velocity at Time 0 & 5 m/s

    Homework Statement http://www.freeimagehosting.net/t/7bf5e.jpg Ok the initial velocity of the car is 5 m/s to the left. Calculate for each situation, the instant time when the velocity of car is : a)null and 5m/s to the right. For situation one with just one pulley: In the...
  40. A

    Bio mechanic force/moment problem sets

    Homework Statement Hi everyone, I have 2 questions that I think are relatively easy but are frustrating in that I just can't seem to get an answer 1st -- If a lateral-to-medial load is applied to the foot, a counteracting moment is produced at the knee joint in a lateral-medial plane, which...
  41. H

    Good textbook for general relativity and quantum mechanic

    I want to get the fully understanding in general relativity and quantum mechanic in the level that I can master it and use it for computation. I can handle most of equation, so please suggest me no matter how complex the equation in the book is. I really want it to do some reserch to send as an...
  42. jaumzaum

    IPhO Training: Circular Motion Homework

    Homework Statement i'm being trained to the IphO (Internataional Physics Olimpyad), and I've come across the following exercise: A F Force is applied to a body initially stopped in a rollercoaster. The F force makes the body describe a circular trajectory at the rollercoaster...
  43. U

    Mechanic of Machine - belt drive system

    Mechanic of Machine -- belt drive system Homework Statement An induction motor shaft, runnnig at 1200 rpm, drives a workshop main shaft by a flat belt drive. the diamter of the pulley on the motor shaft is 40cm n the main shaft is 70cm. another pully of diameter 45cm drives a countershaft...
  44. K

    Question about beam and moment in mechanic engineering

    Homework Statement The beam AB shown is connected to beam BC.Find the reaction at each supporting point and moment at A. Homework Equations This is the FBD given by the lecturer: The Attempt at a Solution Actually,I get the answer but not sure correct or not.These are my answer...
  45. D

    Homemade cylinder/actuator push-button pin/tooth/spring mechanic lock

    i am trying to design and build a homemade cylinder-type puzzle lock. I am willing to accept any comments, both negative and positive. the lock is a cylindrical shaft, with a bolt-type actuator mechanism in the center. when the cylinder rotates to the right, the center ejects. when turned to the...
  46. F

    Automobile mechanic that actually helps

    Thought I ought to share this really fantastic website: http://scottykilmer.homestead.com/contact.html Also this Youtube Channel: http://www.youtube.com/user/scottykilmer I've had a lot of questions already, and he answers all of them FOR FREE! Imagine that--an actual decent human being...
  47. S

    Solve Incompressible Flow Over Converging Duct Oscillating Velocity

    given an incompressible steady flow over a converging duct, the outlet velocity can be found just by using mass continuity equation, v1A1=v2A2. However given a time dependent inlet velocity ie. oscillating velocity, how do i get the outlet velocity? assume the flow is incompressible and...
  48. C

    How Does Bulk Velocity Relate to Maximum Velocity in Turbulent Tube Flow?

    Homework Statement For turbulent flow in a smooth, circular tube with a radius R, the velocity profile varies according to the following expression at a Reynolds number of about 10^5. Vx= Vxmax * [(R-r)/R)]^(1/7) where r is the radial distance from the center and Vmax the maximum...
  49. K

    Scrodinger equation and Quantum mechanic stuff required

    Apply Schrodinger’s Wave equation to calculate energies of particle in a box . kindly refer me to some web material and send some stuff regarding it , also if some one has the PDF files related to Quantum mechanics with solved examples... would be immense help. Regards
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