Conceptual Definition and 874 Threads

Homework Statement you are flying your personal rocket craft at v=o.9c from star A to star B. The distance between the stars, in the stars' reference frame is 1.0ly, bother star happens to explode simultaneously in your reference frame at the instance you are exactly halfway between them...

Homework Statement I don't have a particular problem in mind, just trying to recap a method my professor quickly skimmed over for determining whether a point is a max or a min. I had suggested that we use the second derivative test on our critical to determine whether it is a max or a min...

Homework Statement An object of mass m is initially at rest. After a force of magnitude F acts on it for a time T, the object has a speed v. Suppose the mass of the object is doubled, and the magnitude of the force acting on it is quadrupled. In terms of T, how long does it take for the...

Homework Statement I am worried that I don't understand a basic part of figuring out the component forces in the following problem. I have a full worked example but there is a few steps which I don't understand why we use sin for the x component and not cos (understand why I am really...

Homework Statement When running a moving cart into a relaxed spring, will the force of the spring be constant on the cart? Homework Equations \DeltaP\rightarrow =\rightarrowFnet\Deltat or F = 1/2kx^2? The Attempt at a Solution my guess is that the more you compress or strech a...

Homework Statement A piece of metal turns red when at 1100K while a piece of quartz doesn't "shine" (i.e. emits in the visible range I guess) at this temperature. Explain this phenomenon knowing that quartz is transparent to visible light. Homework Equations None. The Attempt at a...

Basically, I want to practice some of the more conceptual sort of questions (as opposed to straight calculations), but I don't have any! Questions on: -Simple wave motion (universal wave equation type stuff) -Speed of wave in solids -Sound waves (speed of sound, intensity of sound)...

Ques 1) If two bodies are in thermal equilibrium in one frame, will they be in thermal equilibrium in all frames ? Ques 2) Does the temperature of a body depends on the frame from which it is observed ? Ques 3) The length of a brass rod is found to be smaller on a hot summer day than on a...

Sry for a proper wall of text, and it´s probably pretty "chatty" too, as I reason about things back and forth... Plz do feel free to comment on the reasoning since I post it to learn how to think about these things... I believe that I have sometime learned that one can relate refractive index...

Why the area under the curve of the function y=1/x form 1 to inf is infinite. But if we take this area and revolve it around the y-axis we obtain a volume of pi ?

Homework Statement When a sprinter bursts from the starting blocks, he/she generates considerable forward momentum. Is this an example where momentum is not conserved? Homework Equations The Attempt at a Solution I say yes, because there is no interaction of two systems. The...

A momentum question - having conceptual difficulties - please help..! Homework Statement A freight car of mass M contains a mass of sand m'. At t = 0 a constant horizontal force F is applied in the direction of rolling and at the same time a port in the bottom is opened to let the sand...

Homework Statement A proton is released from rest at point A in a constant electric field and accelerates to point B (see part a of the drawing). An electron is released from rest at point B and accelerates to point A (see part b of the drawing). How does the change in the proton's electric...

"weight" problem (conceptual) Homework Statement an object has a mass of 25kg on Earth. If the same object is moved to an inclined plane in Venus, where the acceleration due to gravity is 8.8m/s^2, how does its weight compare to when it was still on earth?? a. Wvenus > Wearth b. Wvenus =...

Homework Statement A block is attached to a horizontal spring. On top of this block rests another block. The two-block system slides back and forth in simple harmonic motion on a frictionless horizontal surface. At one extreme end of the oscillation cycle, where the blocks come to a momentary...

1.Problem: A thermodynamic system has a large number of possible microscopic states. If you double the number of possible microscopic states, what happens to the entropy of the system? it decreases it remains the same it increases, but by a factor less than 2 it increases by a factor...

Hello friends! I have just started a conceptual physics class and have not taken math or science in 6 yrs! Therefore, even some of the most fundamental physics questions are troubling me. I am not looking for answers, just logical steps to proceed with each problem. Below I will post some...

Homework Statement 1.) does a ball thrown upward lose momentum as it rises? explain. 2.)a duck walks along a long thin raft in the water. what does the raft try to do? what hinders this action? 3.)a golfball and a football have the same kinetic energy, which ball has the greatest...

I have a pedagogical question, and a philosophical question, both involving energy: 1) All the derivations I’ve ever seen of kinetic energy in both elementary and advanced texts (or in Physics Forum searches) either simply define T=1/2mv^2 or start by taking the dot product of force and...

This is more of a conceptual question. Homework Statement -------------------- 1.KE_{Max} = hf-\phi 2.\phi = Work Function. The minimum energy required to free an electron with a photon 3.E=hf This it the energy of a photon --------------------- In my book it says that" hf > \phi"...

I have been looking at a problem in magnetostatics about sheets of infinite surface current, positioned along the xy plane. Now clearly there is an Amperian loop parallel to the yz-plane. I understand why there would be no x component of the magnetic field, but I don't understand why there...

Homework Statement In using a ladder where the wall is smooth but the floor has a coefficient Us, why is it necessary to make the angle large? Homework Equations The Attempt at a Solution I'm a little confused by this, because I would think that you would want to make the angle...

Alright, I have a conceptual question regarding Green's Theorem that I'm hoping someone here can explain. We recently learned in my college class that, by Green's Theorem, if C is a positively-oriented, piecewise-smooth, simple closed curve in the plane and D is the region bounded by C, then the...

If you compress a gas in a piston(a monoatomic perfect gas for instance), what is the equation that gives you the temperature of the gas or amount of heat introduced in the gas vs the volume of the gas? And what is the ratio of energy that is transformed into heat vs into pressure? Is it...

Homework Statement In a performance test two cars take the same time to accelerate from rest up to the same speed. Car A has a mass of 1400 kg, and car B has a a mass of 1900 kg. During the rest, which car: a)Has the greatest change in momentum? b)Experiences the greatest impulse? c)Is...

Hi there, I've found some conceptual physics which i am confused about. Can anyone help me out? 1) Let's say if a particle is moving along an expanding spiral in a manner that the particle's normal acceleration[B] remains constant. How will the linear and angular velocities change in the...

help! on conceptual potential and radii multiple choice Homework Statement Two positively charged metal spheres of different radii are connected by a conducting wire. Which statement is true about them? a. their potentials are the same b. their charges are the same c. their electric...

Okay, so I've been trying to wrack my brain around this concept for a while but to no avail. PV = nRT (Preal + n2*V-2a)(Vreal - nb) = nRT From these equations, it's clear that real volume is greater than ideal volume under real conditions. I understand that this is because the molecules...

Homework Statement In a galvanic cell, the electrode that builds up a precipitate of metal (known as plating out) is: A. the cathode, and its surface is rich in positive charge. B. the anode, and its surface is rich in positive charge. C. the cathode, and its surface is rich in electrons. D...

Hi there everybody, while not a specific homework problem, in my PDE class i have come along a question which i don't quite understand. Now, when non-dimensionalising an equation, i believe the purpose is to remove the units from it? Now, we are talking about a biological population and are...

On p. 428 of Grinstead and Snell's Introduction to Probability, they say that fair* games with an infinite number of states (Markov states, if the game is a Markov process) need not remain fair if an unlimited number of plays is allowed. The example they give is two people, Peter and Paul...

Homework Statement I have a system with air flowing through a ducting with two inlets and one exit operating at steady state. There is no heat transfer or potential energy change. I know the mass flow rates and velocities at all inlets and exits. How would I go about finding the rate of change...

I just need an explanation: A spinning bicycle wheel is mounted on an axle you can hold in your hands. You hold it in front of you with the axle horizontal. The direction of the angular momentum vector is to your right. You then rotate the axle clockwise in a vertical plane as seen by you...

Is angular acceleration zero in this situation? A cylindrical space station located in distant space, rotates with constant angular velocity about its axis. An astronaut rotates with the station and is located at the perimeter, a distance R from the axis.

Homework Statement One likely theory for the origin of the Moon is that it was formed by the impact of a Mars-sized object on the young Earth. How fast would the object have to be going when it hit the Earth to vaporize enough rock to make the Moon? Homework Equations The Attempt...

Hey Guys, Say you have an air compressor with a constant volume. And were given the temperature and pressure at the inlet. And also, the temperature and pressure at the outlet. Would the mass of the air at the inlet equal the mass at the outlet? When applying the ideal gas law to the inlet...

Hi. I'm not sure if this is the right place to pose this question as it is not homework question. I'm studying RC circuits in second semester physics and I have a question about the electrons traveling through a circuit. Is it true that electrons won't travel down a branch of a circuit in...

Conceptual ---- Work Homework Statement In general, the work done by a force F_vec is written as W=\int_{\rm i}^{\rm f} \vec{F}(\vec{r})\cdot d\vec{r}. Now, consider whether the following statements are true or false: 1) The dot product assures that the integrand is always...

Homework Statement a. A fire engine is moving at 40 m/s and sounding its horns. A car in front of the fire engine is moving at 30 m/s, and a van in front of the car is stationary. Which observer hears the fire engine's horn at higher pitch, the driver of the car or the van? b. A bat flying...

Homework Statement There are two important conditions for a rigid body to be in equilibrium. The first condition is that the net force on a body must be zero. The second condition is that the net torque on a body must also be zero. 2,3. Relevant equations; attempt at solution. I...

Why conceptually, does the ground state for the particle in the box model correspond to n=1 while for the harmonic oscillator and the particle on a ring model it is n=0? For all three models, why don't we consider negative quantum numbers? attempt:...the particle in a box and particle on...

I read some books trying to understand the concepts of physics and here are the parts I got stuck at, if you could help me out, I would move on :) 1. Why can't momentum and position not be determined at the same time?(Heisenberg Uncertainity Principle) 2. How is 1 electron shot at a time...

Good afternoon, First of all, this is not a homework question, but I'm not sure whether it should be posted on the Homework section. My problem arose when I tried to think about what happens when a spring does work in two blocks. First, consider two blocks (1 and 2) on a frictionless...

Homework Statement This was a problem I needed help on. A train is traveling up a 3.73 degree incline at a speed of 3.25 m/s when the last car breaks free and begins to coast without friction. a). how long does it take for the last car to come to rest momentarily? b). how far did the...

Hello all, Q: If an electroscope is positively charged throughout (gold leaves are being repelled), and a very strong rod that is negatively charged, is progressively brought closer to the electroscope... How are the charges distributed? I think that as the negatively charged rod is...

This really isn't a homework problem with specific computations, rather it's a conceptual problem I'm struggling with; hence, the template doesn't really apply. (Please don't delete my thread!) In the derivation of the work-energy theorem W_C = \int_C \mathbf{F} \cdot d\mathbf{r} = T_2 - T_1...

If we have a resonator composed of 2 partially transmitting mirrors/grids and we excite the resonator from one end, say the left side then on the right we expect to get the characterstic transmission comb and on the left the inverse (1-Transmission) reflection curve. Whats giving me a...

Hi there, I've just joined the university for the 2nd week now. My lecturer has gave this homework which i have no idea to solve at all... It is not calculation but conceptual problems. Can anyone please guide me or help me with it? I'll truly appreciate and thanking you so much! Please help T_T

Homework Statement Ted is lying down and attempts to stand up. However Ted stands up too fast, and experiences dizziness. To compensate for this effect, the vessels in Ted's head expand. Why does this dizziness happen and why does the body respond by expanding the vessels in Ted's head...

Homework Statement A proton and an electron are each accelerated for the same distance across a region of constant electric field. Which experiences the larger acceleration? Homework Equations The Attempt at a Solution Would both feel the same acceleration but in the opposite...