Calculation Definition and 1000 Threads

How can we calculate the speed of a vehicle from pedestrian throw distance ? If the weight of a vehicle is 1220 kg and a pedestrian's weight is 72 kg. Throw distance is 20.70 meters.

as B moves to over A, ( A is a fixed point ) C slides up its guide slot and is stopped by a non compressible object and no amount of force can shift it further up. measurements in units. At this point >> how do I know how much pressure C excerts upwards. psi? Mpa? I hope I'm making myself...

Hi How can I measure, shaft power (watts or HP) of a vertical turbine using dead weight blocks Turbine diameter - 18 inches RPM - 450 ( Zero Load)

As you know, resistance of a rectangular shape is given by R=ρ A/L But how do we theoretically calculate the resistance of the bottom case? ( now, the current flow is not parrallel, current flows from bottom through the right side) I would like to know if there is any references for this...

I am not a mechanical engineer; but I have physics background. I want to lift about 250 watts of heat from a metal block. At the same time I have to maintain its temperature at 30 deg Cel. For this I want to use water-air heat exchanger (HE). Heat exchanger will have inlet & outlet pipes. Hot...

I haven't got a clue about where to start with this! I'm building a freestanding heavy bag. Since I live in an apartment I can't hang my bag, so I've decided to build a base to slip my bag onto. I have the materials but not the knowledge. Can someone please help me figure out what the base...

Homework Statement Not sure if this is advanced, so move it wherever. A certain rigid body may be represented by three point masses: m_1 = 1 at (1,-1,-2) m_2 = 2 at (-1,1,0) m_3 = 1 at (1,1,-2) a) find the moment of inertia tensor b) diagonalize the matrix obtaining the eigenvalues and the...

Hi, I have trouble understanding why the following relations hold true. Given the Minkowski metric \eta_{\alpha\beta}=diag(1,-1,-1,-1) and the line segment ds^2 = dx^2+dy^2+dz^2, then how can i see that this line segment is equal to ds^2 = \eta_{\alpha\beta}dx^\alpha dx^\beta . Further, we...

Homework Statement I did some homework and wolfram alpha afterwards gave different result than what I have. Apparently I must have done some error, but I couldn't find error after I doublechecked about two times. So I decided to see if you guys can find an error. And what is the correct answer...

Homework Statement Taking atmospheric pressure at sea level to be 1x10^5 pa CPa and the density of air at sea level to be about 1.2kg/m^3,estimate the atmospheric pressure in London 550m above sea level. For this calculation, it is easiest to assume that air density doesn’t change with height...

Homework Statement Homework Equations ε= r_max - r_min / r_max + r_min = r*v2 / gRE The Attempt at a Solution I first find that 1 revolution is 2π rad , the angular velocity ω = 2π rad / 24h = π/43200 rad /s so v = rω where r is the unknown ε = 0 (circular orbit) r*(rω)2 / g RE = 0Correct...

Hi I was given the following problem in my coursework: Homework Statement "A spring is initially compressed by 50mm when a steel ball of mass 2kg is released from just being in contact with the uncompressed spring. Determine the spring stiffness (k) of the spring." Homework Equations F = mg...

Homework Statement for the elongation due to its own weight , i suspect the calculation of elonation due to its own weight is wrong ... Homework EquationsThe Attempt at a Solution I think it should be (3456.3825)(75) / (300x10^-6)(200x10^3) = 4320m = 4320x10^3 mm , right ? [/B]

Hi I'm working on a project out in the North Sea on an oil rig, we need to remove a hydraulic cylinder from a crane, I have attached a drawing the red cylinder B needs to be removed. To do this we will move the crane boom to the position shown by the orange lines and rest the end down on the...

Hi, If E[wwH]=T, where w is a zero-mean row-vector and H is the Hermitian transpose then assuming that H is another random matrix, it holds that E[H w (H w)H] = T H HH or T E[H HH] ?? In other words, the expectation operation still holds as in the latter expression or vanishes as in the...

I am not a mathematician but enjoy studying the primes as a mechanical system. Regrettably I don't have the tools (and perhaps the intellect) for some jobs. I've spent some time trying to calculate the probability of a number being a product of each successive prime as the number line is...

I have a question about calculating solubilities of sparingly soluble salts. Eg Ksp CaF2 = 4 x 10-11 So, Saturation Index of CaF2 is: SICaF2 = IP / Ksp Where IP = Ionic Product = [Ca2+] x [F-]2 [Ca2+] and [F-] are molar concentrations of each ion. Example: We have 400 ppm Ca and 12 ppm...

If Have have the torque needed to turn the input shaft of a 500:1 Gearbox with no load, can that information allow me to calculate the opposite. I want to know the torque required to turn the output shaft. What I mean is, if you were to apply the force to the output shaft. In other words, use...

Homework Statement Hey :-) I just need some help for a short calculation. I have to show, that (\sigma \cdot a)(\sigma \cdot b) = (a \cdot b) + i \sigma \cdot (a \times b) The Attempt at a Solution I am quiet sure, that my mistake is on the right side, so I will show you my...

Homework Statement So i have to calculate the Clebsch-gordan coefficients for the state j1=3/2 and j2=1/2[/B]Homework Equations Recursiom formula, lowering and uppering operator[/B]The Attempt at a Solution I have tried to calculate the first set of the coefficients stating that: L- l2,2> =...

May I start by saying hello to all and that I have visited the site before, but have yet to create an account until now. With that said, I am having difficulty calculating proper numbers for a project I am designing. Mind you, it has been about seven years since I was in any physics or...

Homework Statement Given the scheme https://www.dropbox.com/s/nm943gleo2nc8ft/Screenshot%202016-08-28%2013.47.33.png?dl=0 Springs' constant k=40 N\m mass of bulk m=6kg The wooden bulk is released at rest when all the springs are not stretched Question: What is the elastic total maximal Energy...

Let's say I have a GPS unit that reports an "accuracy" (this is what the GPS device reports as the uncertainty in the measurement of position) of 15ft. I travel some distance, with the GPS reporting a position every second. At the end of 1000 seconds I arrive at my destination. For the sake...

Hello :-) I have a small question for you :-) 1. Homework Statement The Operator e^{A} is definded bei the Taylor expanion e^{A} = \sum\nolimits_{n=0}^\infty \frac{A^n}{n!} . Prove that if |a \rangle is an eigenstate of A, that is if A|a\rangle = a|a\rangle, then |a\rangle is an...

Hi, I have following two parameters with me a) Maximum three phase fault current in amperes (A) and phase angle in degrees (B). I want to calculate the positive sequence resistance (R) and reactance (X) from above two variables for a symmetric system. I couldn't figure out a way to find R and...

Hi, When I type into my calculator 13.6/(1.000000001) the calculator returns the answer 13.59999999 Then, when I type 13.6/(1.0000000001) the calculator returns the answer 13.6. Obviously, both 13.6/(1.0000000001) and 13.6/1 cannot equal 13.6, so what's the deal with the calculator...

Hi team In my one of the application I have to use the gear box to rotate 500 kg load I have to use handwheel to rotate I am using the formula Torque= force x per. Distance x coefficient of friction = 500x.7x.8 : 2800 Nm Is it correct to calculate the torque I have attached the image for...

I'm trying to figure out how fast an object will fall/accelerate with a constant upward force applied to it. For instance, a 100 lb object with a 25 lb upward force applied to it. Would it fall/accelerate at the same speed as a 75 lb object?

Hi - I'm trying to figure out the specific steps in a math textbook. I'm trying to figure out how the textbook did its algebra here with a quadratic formula to find an inverse of a function: Sadly there's a step I'm supposed to know by now in the simplification algebra in there 3 steps...

My question is more general but I explain it by a simple example i.e. graphene and tight binding method. I solved energy dispersion of graphene with tight binding by the two ways: First, I took graphene as a lattice with the two basis atoms A and B. In the second way, I took graphene as a...

I would like some help in working out the correct unit of concentration in the question below please. I added a substance which has a density of 1.020 kg/m3 to a sample at a rate of 800 uL/ L of sample The substance is also 60% w/w. Will the final concentration in the sample be in 490 ug/L or...

Hey guys.. Sorry for my english, i'am only 16 and it's not my parent language. I need help about a problem on mechanical engineering, and i really appreciated if you can help me out. I assume that I've got a moter currents which gives me out 220-230 Volt trend, and has 1800 bends per minute. Now...

An incomplete reaction of 12.125 g of propane proceeds as follows: 3 C3H8(g) + 14 O2(g) → 8 CO2(g) + 12 H2O(g) + C(s) How many grams of solid carbon residue are produced as a product? So, C3H8 C=3(12.01)=36.03 g/mol. H=8(1.01) = 8.08 g/mol. =...

Hello people smarter than me. I am working on a project that utilizes a gas shock to open a guard that protects machine components. A very common scenario. I have nailed down my positions for where the shock is mounted, pivot point, shock length, stroke, guard CG etc... I have tried to do the...

I am looking for guidance on how to successfully measure vacuum using a device similar to a pirani gauge, my device however is a tungsten filament which is heated electrically to about 90*C, and it's current draw is a measure of vacuum.The problem I am having is how to relate specifically the...

Hello folks. Newbie here. I hope this is the right place to post my question. I'm trying to do a calculation and find it's beyond me. Here's the challenge. Let S be the set of all primes up to P. Let P! be the product of the primes in S. For incrementally increasing values of P I want to...

Hi All. Please can someone help? I have a question regarding calculating heat load and required surface area for a single effect evaporator. Details: Solution Feed rate 1.1kg s-1 Solution feed concentration 8%, concentrated to 30% Feed solution at 60 degrees Celsius with Specific Heat Capacity...

Hi i have calculated compressor , combustor , turbine inlet and outlet temperature , pressure so on and my output of gas turbine is 50MW , So for this i want to calculate the mass flow rate of air and fuel in compressor , combustor , turbine . Like m0=?,m1=?fan inlet,m2=? compressor inlet,m3=...

Hi Guys I'm new the PF and hope I'm posting I the correct place, apologies to admin if not ;-). I'm working on a project at home and maths is not my strong suit. I have an equation that I need to complete and involves converting thermal heat capacity in water into electric power. From what I...

Hi all, I'm referring to the paper Chem. Phys. v.26 pp.169-177 y.1977 from Cederbaum, Domcke and Köppel where the expressions for linear vibronic coupling parameters are derived in second quantization notation. I'm stuck on the point, where the dependence of the fermionic ladder operators on...

Homework Statement // given in JavaScript var amount = parseInt($('input[name="amount"]').val()); var downpayment = parseInt($('input[name="downpayment"]').val()); var interest = parseInt($('input[name="interest"]').val()); var months = parseInt($("#months").val());Homework Equations What is...

Homework Statement Homework Equations v = w x r The Attempt at a Solution I got the answer correct after a few tries, but I am little confused on why it has to solved this specific way. I know that v = w x r, so why can I not just say w = v/r? Is it because w is measured from the center of...

Homework Statement Suppose a spaceship starts from rest from a space station floating in deep space and accelerates at a rate of |a| relative to the space station for 1.0 Ms. It then decelerates for the same amount of time at the same constant rate |a| to arrive at rest at another space station...

hello! i was provided by the radii from 0 to 5 cm and a parabolic profile is also given .. in numeric form i was asked to calculate the flow rate how to understand it to solve further kindly help ...

In what scenarios would you use the equation g= F/m instead of g=GM/r2 (or vice versa), for calculating gravitational field strength? Update: is g=F/m used to find the force acting on a mass in a gravitational field (of strength g), whereas g=GM/r2 used to calculate the gravitational field...

Homework Statement You may use pen-and-paper and mental calculation. You have 6 minutes time. Give final digit of $$ (22)^3 ~+ (33)^3~ +(44)^3~+(55)^3~ +(66)^3~+(77)^3 $$ Homework Equations 3. The Attempt at a Solution [/B] I'm not terribly good at mental arithmetic myself. I was never...

Homework Statement Ammeter shows 1.2 A and 1.0 A. How large amount of charge passing through the lamp in 1 minute? https://physicsforums-bernhardtmediall.netdna-ssl.com/data/attachments/84/84982-6e293679b3592fb475f0f9cac697526f.jpg Homework Equations Q=I*t[/B] The Attempt at a Solution I =...

Homework Statement How many grams of K2Cr2O7 (350 g 6,50%) must be added to get saturate the solution at 20C (12,6 g/100 g)? Homework Equations The Attempt at a Solution 350 g x 0,065 = 22,75 K2Cr2O7 I got 10 g, but it's not correct. The correct answer is 18,5 g.

Homework Statement An electric fish is capable of generating a voltage of 220V. This drives a pulse of 15A lasting for 2ms. The fish produces 200 pulses in one second. What is the average power output? Homework Equations P=VI P=E/t The Attempt at a Solution At first glance I thought we just...

*WARNING* My understanding of maths is pretty limited and i don't know if i am being really stupid or not. Ive been looking into data analysis of football matches, working out proabilities of certain situations happening and how steady the averages are. i come across a website which as really...