# What is Mechanic: Definition and 121 Discussions

A mechanic is an artisan, skilled tradesperson, or technician who uses tools to build, maintain, or repair machinery.

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1. ### Determine the velocity of a package dropped from a satellite

Momentum before ejection P_b: P_b= (M+m)*v_M=8*500=4000, since the package is still on the satellite and isn't moving. Momentum after ejection P_a: according to the law of conservation of momentum P_b=P_a, and this gives me: 4000=450*8 + v_m*50 => (4000 - 3600)/50 = v_m = 8 km/s But according...
2. ### How Effective Are Electro-Muscle Fibers in Robotic Drives?

Project for creating electro-muscle fiber for robotic drives The drive consists of a central spiral guide and external thin conductors as (muscles) as well as coils at the ends of the muscle, and is in a strong elastic casing. Do you think how effective such a muscle will be and from which...
3. ### Find the man's tension pulling the rope

The elastic force of the board,N=G_1+G_2=1000N. The kinetic friction f=μN=200N. The tension T=f=200N.
4. ### Feynman's Lectures exercise about Newton's laws

TL;DR Summary: Solutions to an exercise coming from the famous "Exercises for the Feynman lectures on physics". I'm stuck on an exercise. "A mass ##m## (kg) hangs on a cord suspended from an elevator which is descending with an acceleration of ##0.1g##. What is the tension T in the cord in...
5. ### Relationship between horizontal force and friction in an exercise

The thing with this exercise is that I don't think that the question makes sense at all (or, at least, is incomplete). First of all, we don't know if the mass moves with any of those tensions, therefore I cannot know which coefficient apply. Second of all, even if we suppose that the mass is...

16. ### Angular momentum of a particles in the form of ##L = mr^2\omega##

##\vec{L} = \vec{P} \times\vec{r}## ##L = mvr sin \phi##, where P = mv Since ##\vec{r}## and ##\vec{v}## are always perpendicular, ##\phi## = 90. Then, ##L = mvr## At this point, I don't see how to get ##L = mvr = mr^2\omega##, using ##\omega = \dot{\phi}## I know that ##\omega =...
17. ### A mass collides with an inclined plane

In my textbook, it is stated that "if an object elastically hit an frictionless inclined surface with angle between the vector of initial velocity and an imaginary line that is perpendicular to the surface ##\alpha##,then the angle between the line and final velocity vector will also be...
18. ### Conservation of momentum in an oblique launch and projectile explosion

This problem I already solved using another resource (just get the coordinate of the center of mass reach and from it, get to the larger mass. R = (3v02) / (4g)). But I'm having some trouble calculating using moment conservation. Here what I've done so far: $$3\vec v_0 = \vec v_1 +2\vec v_2$$...
19. ### Kinematic diagram of a gear mechanism

Can anyone help me with a kinematic analysis for the mechanism attached below? I need the outline of the mechanism, its notes and the necessary formulas to find out the transmission ratio and the rest of the values.
20. ### I The center of mass & relativistic collisions

In special relativity (especially relativistic collisions), is the center of mass frame as useful as Newtonian mechanics?

22. ### Calculate the output power for da Vinci's tank mechanism

Hello everyone. I'm working on 3D animation about da Vinci tank and why it doesn't work. Please help me find out how to compute: 1: how many men need to move this machine 2: what power on wheel can produce different number of man, like 1, 2, 4, 8.. vehicle mass = 8t men strength = 60kg lever...
23. ### How Do You Calculate the Acceleration of a Box on Banked Wheels?

A homogen box with the mass M rolls without sliding on two round wheels. The wheels with mass mass m are also homogen and roll without sliding, on top of the banked Surface. We use Gravitation g. Find the accelration xM of the box I don't know which solution is correct. i got 0.67 m for xM...
24. ### Analytic solution of the Earth's orbit around the Sun

The exercise is to compare numerical and analytical solution. I have worked out the code from earlier exercise (see code under this text), but I don't understand how the analytical solution works. I have tried to use the equation r(theta) = a(1-e^2)/(1+e*cos(theta)), which is OK but I don't...
25. ### Write an expression w1 of the angle shown in the first picture

A bicycle wheel rolls at a constant speed along a circular path on a horizontal surface. The wheel has a constant angle of inclination to the vertical direction and the distance from its center of mass G to the fixed Z axis is R. Determine the relationship between the angular velocity w1 around...

27. ### Measuring position, velocity and acceleration in relative motion

Well, ##r(t)## in ##A## is just a vector ##(0;y)## because is tangent to the trajectory. Then, from the perspective of ##B## the particle moves in an uniform circular motion. Is this right? The velocity from ##B## must be ##\omega##, right? And what about acceleration?
28. ### Pulley system with relative motion

Well, first I tried to understand the relation between the velocities and accelerations of both bodies and I got that the velocity of ##B## is half the velocity of ##A##. This is because a change in length of the cord "that touches ##A##" must be equal to the change in length of the two cords...
29. ### Calculating the radius of curvature given acceleration and velocity

Well, what I've done so far is calculating the magnitude of velocity and acceleration replacing ##t=2## in ##\theta (t)## and ##r(t)## so I could get the expressions for ##\dot r##, ##\dot \theta##, ##\ddot r## and ##\ddot \theta##. But that's not my problem... my problem is related to the...
30. ### Chain Hangs Over a Pulley and Starts Moving

Homework Statement: A chain hangs over a pulley. Part of it rests on a table, and another part rests on the floor. When released, the chain begins to move and soon reaches a certain constant speed v. Can we find the height h of the table? I think this question need some tricks. I've tried some...
31. ### Formula for fictitious moments

Hi All, Everyone knows so called "fictitious" forces, also known as "inertial" forces. They are forces felt by some mass point placed in a non-inertial frame. For example: a ball in a moving car or in a carousel. Maybe most intuitive fictitious forces are centrifugal forces, but there are also...
32. ### How to calculate mechanic power a person outputs?

Hey all, I am doing some work to brush up my acoustics and one of the problems I came across this goes like this (translated, so sorry for potential grammar mistakes although I'll do my best to avoid them): A singer exhales 0.1 Litre Air per second. The 'overpressure' (pressure difference, so...
33. ### A ball (sphere) rotating along a moving incline

Homework Statement We have a ball of mass ##m##and radius ##r##. it is placed on an incline (We don't know the angle of the incline, nor we do whether the angle is constant along the incline - maybe it is a curved incline) and then released. The COM of ball is ##h## meters above the incline at...
34. ### Air resistance in projectile motion

In lower-division physics classes, air resistance is usually ignored to make the mathematics of projectile motion easier to understand. When air resistance is included, it's often stated that at lower velocities, air resistance is proportional to the velocity of the object, Fair ∝ kv At...
35. ### A transmission system exercise

Homework Statement We have a transmission system (plate-pinion), with a 38-tooth chainring and a 14-tooth sprocket. The distance between the crank (between the chainring and the pedal) is 170 mm and the pedal is overloaded with 60 kg and pedalled at a speed of 70 min-1. Homework Equations P =...
36. ### A Quantum Mechanic Symposium London

What do you think about Herman Batelaans presentation? https://www.fetzer-franklin-fund.org/media/quantum-forces-and-non-dispersivity-in-the-aharonov-bohm-effect-batelaan-video/
37. ### The phase of a simple harmonic motion

Homework Statement How can I calculate the initial phase in a simple harmonic motion if I only have the amplitude, frequency and angular velocity as data? Homework Equations The formula of the position, in fact they ask me to do the formula that allows to know the elongation depending on the...
38. ### How can I use Poisson bracket to find P in a canonical transformation?

Homework Statement q,p transforms canonicaly to Q,P where given Q=q(t+s)+(t+s)p ,t is time and s is constt To find P Homework Equations Poisson bracket {Q,P}qp=1 The Attempt at a Solution Using Poisson bracket I find (t+s)*(dP/dp-dP/dq)=1
39. ### Question - Mechanical (two-piece carrier)

<<<Moved from another forum. No template. >>> I have to solve this mechanical Problem... I solved it, but I get fpór By=0,448F (see at my calculation!) and the right answer is 0,3F...what did I wrong? I should solve A B C! B is a two-piece carrier. F and a is given!
40. ### Mechanical problem -- a mass sliding down a curved ramp

Homework Statement An object which has mass = m is released from point A which has height of h. The object moves along the rail with no friction. The rail OB is a semicircular rail which C is the center and R is the radius. If the object falls from the rail at the point B, find the following...
41. ### Help Understanding the answer to a Quantum Mechanic problem

Homework Statement The answer is as follows: [/B] However they said that time t=0 so I am confused how the exponent has a t in it surely it should be zero. Thanks
42. ### Find the initial acceleration of block B

Homework Statement a block B of negligible mass is connected to a particle of mass 1 kg with a non-stretchable string. Now the hanging particle is given a velocity root(8gH) horizontally when system is at rest. Find the initial acceleration of block B. Homework Equations 3. The Attempt at a...
43. A

### Spring angles at static equilibrium on application of force

Homework Statement Two linear springs with stiffness Kh, Kv are attached to a single mass m at right angle to each other, i.e; one of the spring(Kh) is in the horizontal direction(x-axis) and the other(Kv) is in the vertical direction(y-axis). A constant force F is being applied to the mass...
44. K

### Dynamics of a point mass in circular motion

Homework Statement Dear All, I'm having a hard time solving the following problem: A point of mass is moving on a circular plane (Oxy), where the circle's formula is: The force acting on mass "m" is defined as: We're looking for velocity of point "m" in position (1,1) =V1, and in position...
45. ### Can Access to Science Courses Provide a Path to Physics Mastery?

Hi. I am new to PF and I hope to learn some Physics, and chat to like-minded people. I am currently taking an Access to Science course, which is the equivalent to 3 A Levels - Biology, Chemistry and Physics. Hope to learn from you guys!
46. ### B Quantum mechanic has something to do with electromagnetism?

Hi does the quantum mechanic play a role in the intrinsic nature of electromagnetic fields and its propagation? massi
47. ### Calculating Tension in a Revolving Mass: Homework Solution

Homework Statement The figure shows two wires that are tied to a 970g mass which revolves in a horizontal circle at a constant 7.5 m/s. What is the tension in the upper wire? The wires are both 1m long, and are attached to a pole. The radius is cos(30 degrees). It's an equilateral triangle...
48. ### 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...
49. ### 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 ?
50. ### 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).