Constant Definition and 1000 Threads

Homework Statement I have a lab where I have to use two methods to find the capacitance of printer paper. Homework Equations C = kAeo / d The Attempt at a Solution From these slopes, I got k = .897 for the first type (using changing distance between the plates of the capacitor) for the...

Hey all, was watching my downloads today and saw that my download speed was dropping at such a rate that the eta of the download was almost constant, so I was wondering what negative acceleration would be required for the eta to be constant, if time left is size/speed, speed is first derivative...

If a car is traveling at a constant speed of say, 60MPH, is the acceleration of the car 0, or is it equal to the drag and rolling resistance it's facing?

How can a time constant, in parallel plates, be the original value without changing the capacitor?

Homework Statement A mass 2.74 kg is hung from a spring. The mass is pulled down a short distance and released, it oscillates with a frequency f = 1.972 Hz. What is the spring constant for the spring? Homework Equations f=1/2pi*sqrt(k/m) The Attempt at a Solution 1.972 = 1/2pi*sqrt(k/2.74)...

I've read that drag coefficient depends on the shape of the object but I am confused as to what shape means. Does it mean geometric shape or is area included in that? Say I have one sphere of radius r and keep fluid velocity, density, and viscosity constant and find its drag coefficient. Would...

The question is: If quantum mechanics were detectable in planetary orbits, how much larger than the currently accepted value would Plancks constant need to be? Relevant equations ΔxΔpx ≥ħ/2 p=mv Earth-Sun dist 1.496E11 Earth orbit speed 28,900ms^-1 Earth mass 5.972E24 kg The attempt at a...

The Problem: A 1.80 mol sample of an ideal gas is compressed isothermally from 58.1 L to 15.6 L using a constant external pressure of 2.72 atm . Calculate W: Calculate Q: Calculate ΔU: Attempt at solution: I tried W = P(ΔV) to no effect, W = nRTln[Vf/Vi] to no effect. The online...

Hello all, is there an alternative way of displaying ##\frac{x}{e^{x}-1}## as a trigonometric function, not using the bernoulli-numbers ? Thanks in advance

1:question A weight W is suspended from a rigid support by a hard spring with stiffness constant k . The spring is enclosed in a hard plastic sleeve, which prevents horizontal motion, but allows vertical oscillations. A simple pendulum of length l with a bob of mass m (mg<<W) is suspended from...

Homework Statement the volume density of a body centered cubic lattice is 5.3*10^22 Calculate the lattice constant, effective radius of atom, surface density on 110 plane, and distance between two nearest parallel 110 planes. Homework Equations 4/a^3= volume density 2/sqrt2*a^2 The Attempt at...

Homework Statement A material contains two types of atoms (A and B) in a zincblende structure. Atom A is group V with a hard sphere radius of 2.5 Å. Atom B is group III with a hard sphere radius of 1.6 Å. (a) What is the lattice constant of this material assuming that nearest neighbour atoms...

I have a variable voltage constant current power supply 0-300v at 50mA. Is it possible and if so what would be the simplest way to have a parallel circuit with 0-300v 50mA on one side and 0-300v 50uA on the other? A simple resistor isn't going to work because the supply maintains 50mA. Any help...

Homework Statement Two cars travel towards one another on a 21.0m road, the car traveling to the left has an acceleration a_L=2.4m/s^2 the other car an a_R=1.8m/s^2. What is the distance traveled by the left car up to the meeting point? Homework Equations Left Car...

Homework Statement a) A material is composed of two atoms, A with effecitve radius 2.00 angstroms and B with effective radius 3.10 angstroms. The lattice is a body-centred lattice. b)Enter the volume density of either the A or B atoms in atoms/cm3 Homework Equations .5*sqrt3=(r1+r2) surface...

Homework Statement "A jet plane is cruising at 300 m/s when suddenly the pilot turns the engines up to full throttle. After traveling 4.0 km, the jet is moving with a speed of 400 m/s." Homework Equations "What is the jet's acceleration, assuming it to be a constant acceleration?" The Attempt...

I listened to a lecture the other day that some anomalies in observations compared to theory caused Max Plank to derive his famous Constant.

Homework Statement [/B] 1. Rob throws a baseball upwards at 14.2 m/s. His friend, John, is sitting in a tree 4.5m above Rob. a. Calculate how long it will take to reach John. b. If John misses the ball as it moves upwards, how long will it take to reach John again. Homework Equations...

Homework Statement A railway engine of mass 100 tonnes is attached to a line of trucks of total mass 80 tonnes. Assuming there is no resistance to motion, find the tension in the coupling between the engine and the leading truck when the train: (a) has an acceleration of 0.020 ms-2, (b) is...

I have been studying that velocity = displacement / time. Now what if displacement / time always gives me same value - does it means that object is at rest as displacement is same then the body has not moved at all. So in above graph velocity is constant - ie displacement wrt to time is same...

Hello! me and my friends were discussing a few ideas earlier this week and then we suddenly started talking about Einstein's biggest mistake. I was a bit lost because I am not all that familiar with the Cosmological constant and I was wondering how can probability be applied to that mistake?? I...

I'm trying to determine how exactly gear ratio limits velocity. I know that a high torque configuration is generally regarded as low speed, but my calculations do not seem to support that. Basically, I've written a small problem where we have an input gear with constant torque and an output...

Hello folks, I need some physics help. Some background to get us on the same rails :) I am developing a 2D game in my spare time. Player controls an object (aka spaceship) in open space (no gravitation influence) by selecting a point in space. A constant force which is always pointed at the...

Using an eddy current brake, one would expect the damping constant ##δ## to increase with the current ##I## supplied to the eddy current brake. My question is, why is ##δ## proportional to ##I^2## and not merely ##I##? The magnitude of the eddy current is ##\frac{1}{R}\frac{dΦ}{dt}##, which is...

ZapperZ submitted a new PF Insights post Why Is Acceleration Due to Gravity a Constant? Continue reading the Original PF Insights Post.

If I'm traveling on a spaceship at a constant velocity (say 10000 m/s) towards Mars will I feel weightless, or will I feel nearly weightless because I will still be slightly affected by gravity? I know that when astronauts are in the ISS they feel weightless because they are in a constant...

Hi, I was wondering if there is any need in the theory of relativity for Newton's Gravitational Constant 'G' to remain a fundamental constant. Constant in Coulomb's Law can be expressed in 'c' and 'pi', then why Constant in Newton's Law needs to be a fundamental constant??

Consider the following diagram of a projectile motion (##\hat{\bf i}## and ##\hat{\bf j}## are the unit vectors of the ##x## and ##y##-axis respectively) We know that $$F=ma.\tag1$$ This can be rearranged to $$a=\frac Fm.\tag2$$ So there are actually two accelerations, one with magnitude...

In a car moving at constant acceleration, you travel 250 m between the instants at which the speedometer reads 40 km/h and 80 km/h. How many seconds does it take you to travel the 250 m? What is your acceleration? I have thought of finding the average of 40 km/h and 80 km/h to start the problem...

Suppose we have a system of particles that interact via conservative forces. I wish to prove that ##K+U## is a constant of the system with tensor analysis. Here is my procedure: The Lagrangian is ##L=\frac{1}{2}m_i\dot{ r_i}^2-\Phi## Lagrange's equations ##\frac{d}{dt}(\frac{\partial...

You and your friend are in building four equal-length blocks apart, and you meet for lunch. Friend is 1.2 m/s and you are 1.6 m/s. The restaurant is between the two building and you and your friend will arrive at the same instant if both of you leave the buildings at the same instant. In blocks...

How do we know the speed of light is constant? Is it possible that we only perceive it as constant?

İn some fixed point theory books, I saw an expression...But I didnt understand what this mean...Please can you help me ? " It was important in the proof of banach contraction principle that the contraction constant "h" be strictly less than 1. Than gave us control over the rate of convergence...

Homework Statement What's up guys, I'm stuck on #2 of this worksheet,http://luc.edu/faculty/dslavsk/courses/phys111/homework/phys111-2015hw1.pdf The half - life of C - 14 is 5730 years. Determine the value of its decay constant (and express the answer in appropriate MKS units). 2.The attempt...

Homework Statement From the experiment I did my force was equal to 0.0686N +/- 0.00196N and my x (rubber band stretch) was equal to 0.003m +/-0.002. The question asks to determine the force constant k +/- ∆k. Homework Equations F = kx k = F/x ∆k = |k| ∆x/x +∆y/y The Attempt at a Solution k...

Here is a question that might be somewhat more philosophical than this community cares for. If so, I apologize in advance. Are there any reputable theories as to why the speed of light is constant? I know that it is an empirical fact and therefore that it does not need to be proven. But on...

Try as I may, I can't figure out how to even phrase the following in a way to google it, so I apologize in advance if it is a trivial question, I am no physicist. What I am trying to discern is if there are very very small shifts in the perceived charge of an atom over very very small amounts...

How would I go about finding temperature distribution in a thin square plate during the the first few milliseconds (or actually a fraction of a millisecond) after t=0s. Initial temperature distribution throughout the plate is known, there is heat flux to one side = Qinj, while heat flux from all...

Homework Statement I don't get how you can use x and p instead of delta x and p in Heisenberg's principle. Also why is it just h bar? Isn't it supposed to be h bar/2? Problem 2-iv Homework Equations delta x* delta p >= h bar/2 The Attempt at a Solution I tried to deal with this problem but I...

Homework Statement A boat is sailing starting from x = 200m. When interpreting x(position) vs. t(time) graph for this boat with math models x = -20t + 200(t<=10), Is it right to say "The boat is approaching to the origin" ? (When t <= 10) Homework Equations x = -20t + 200(t<=10) The...

My GF and I got into a petty argument about pressure washers. She believes that the constant back-pressure you feel holding a pressure wand increases the closer you hold it to a wall (for example). Where as I believe that if the wand had a constant psi, with outward pressure, wanting to force...

Dear friends, Does anyone know how we can solve the TOV equations for a non constant density? In all the references, I just saw the solution for a constant density. Thanks in advance for the help :)

Hello everyone. I am having some problem with dark energy and the cosmological constant. The cosmological constant is a proposed form of dark energy. Alright, now the cosmological constant is is estimated by cosmologists to on the order of 10^-26 kilograms per cubic meters. But the density of...

HI Guys .. I really need some help on this ... I need to manufacture(mix) a liquid that 'displays' as UV light if that's the correct term. any ideas where I could start ? I have limited chemicals knowledge :/

Homework Statement Determine Kepler's third-law constant Ku for Uranus using the data for the first four moons. Homework Equations [/B] (r)^3/(T)^2 = K Data: Moon #1 (Ophelia) r=5.38 x 10^4 km T=0.375 Earth Days The Attempt at a Solution [/B] I know the question asks for the K constant...

Homework Statement Problem: [/B] Given the mass spring system solve for k1 The natural frequency wn = 10 s-1 k1=2k2 m=1kg Homework Equations wn=(k/m).5 The Attempt at a Solution solve for k1 m x w2n =2.5k1 k1 = 40 N/mNote: I calculate 40 N/m and the solution states 250 N/m. I think I...

In one book of Susskind I found the following claim and I wanted to ask for its basis. Susskind says that each kind of boson gives positive contribution to the cosmological constant (the lighter, the better). Each kind of fermion gives negative contribution to the cosmological constant. Thus...

Hi, A capacitor has both its terminals connected together using a wire in a rather lengthy circular fashion, hence acting as a significant inductance. If the area encircled by this 'circuit' is subjected to a linearly rising magnetic field (B=k x t) where k is a constant, the emf induced -due...

Homework Statement Consider a free particle, initially with a well defined momentum ##p_0##, whose wave function is well approximated by a plane wave. At ##t=0##, the particle is localized in a region ##-\frac{a}{2}\leq x \leq\frac{a}{2}##, so that its wave function is...

Pictured below was a problem shown in class with solution. I didn't have time to ask the professor a question about the last step involving an additive constant. V is potential energy, re=Earth radius and z is distance from Earth's surface. What is an additive constant, and how does it...