# Mechanic Definition and 53 Discussions

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

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2. ### I Stuck in understanding Newton's 3 laws

I'm stuck to understand 3 laws of Newton. It doesn't make sense to me. 1. Suppose the case when a person stay in a rest vehicle.When we accelerate the car the person still at rest so the person has to move to the tail of the vehicle cause his intertia of staying rest. If we decrese the...
3. ### B Various Work and Energy laws

Hi, everyone! There are a lot of work energy conservation laws and I get confused which one of them summarizes all of them. Which one I should keep with me and rest should be easy to derive on spot ? 1. ##\Delta E_{mec}=0## 2. ##\Delta E_{mec}=W_{ext}## 3.##\Delta E_{mec} + \Delta...
4. ### Calculate tilt angle of a bar lifted via two ropes on fixed points

Summary: How to calculate the equilibrium angle of a bar that is lifted on its two ends with ropes attached to fixed lifting points? Hello and good day all, First of all I would like to apologize in advance for my english, I am not a native speaker so some grammar errors may be left. My...
5. ### Looking for a manufacturer to build a custom compound bow for me

Hello I am looking for a manufacturer or mechanic that can build my custom compound bow. It doesn't have to be a big business. I would appreciate any help. Thank you
6. ### Should this be a worry? (Trouble with Challenge Problems in University Physics by Roger Freedman)

Ive been reading University physics by roger freedman, I’m on section 3 motion in 2d. I can solve most of the problems ag the end of the chapter, or at least understand the solutions. But there is a small extra section called challenge problems. There’s only 3 but I found them very difficult...

11. ### 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.
12. ### I The center of mass & relativistic collisions

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

14. ### 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...
15. ### 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...
16. ### 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...

18. ### 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?
19. ### 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...
20. ### 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...
21. ### 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...
22. ### 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...
23. ### 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...
24. ### 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...
25. ### 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...
26. ### 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 =...
27. ### 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...
28. ### 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
29. ### 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!
30. ### 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...
31. ### 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...
32. 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...
33. 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...
34. ### Tension problem, check my work?

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...
35. ### 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...
36. ### 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 ?
37. ### I What is more probable?

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).
38. ### 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)...

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...
40. ### Where to get custom jumpsuits

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:
41. ### Newton's third law confusion

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...
42. ### Total distance covered .

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...
43. ### 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...
44. ### 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 [Broken] Homework Equations f=ma kinematics relative acceleration The...
45. ### Find centre of mass

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...
46. ### 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...
47. ### 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...
48. ### 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...
49. ### 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?
50. ### 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.