Confusion regarding direction of kinetic friction on inclined plane.
please help! The formula for kinetic friction acting on a sliding body is μkN When the body is sliding with constant velocity down an inclined plane fk=μkN When the body is sliding up the inclined...
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force to keep the folding doors
Hello, I would like to ask you to calculate the force F, which needed to keep the folding doors in this position. I would like to know what is the procedure for calculating forces. For each answer,...
View ArticleHow many joules expended for a push up?
Just wondering if any of you can do the calculation that well approximates the amount of joules expended by a push up.
View Articlethin glass in liquid
I have one question about optics because I start interested in it. If an object is placed a distance p from a thin glass lens (index of refraction n), we can see its image on a screen that is placed a...
View ArticleLearning curve of Electromagnetism?
I'm taking a first year physics course and have been having a little trouble with the basics of newtons laws and forces and whatnot, though nothing that can't be fixed with a bit more hard work. I'm...
View ArticleCalculating Steam Pressure in Closed Container
I am trying to calculate the volume of liquid water i need to place in a sealed container in order to obtain 10 psi of steam pressure in that closed container. Here are the numbers: Temp: 816 C Volume...
View ArticleFrictional Force Equation Doesn't Make Sense
Frictional Force is mathematically defined as: Ff = μ*m*g*cos(θ) , where μ is the coefficient of friction, m is the mass of the object, g is the acceleration due to gravity and θ is the angle of the...
View ArticleCalculus of Variation - Classical Mechanics
I'm reading Classical Mechanics (Taylor), and the 6th chapter is a basic introduction to calculus of variations. I'm super confused :confused: I've tried to go to other sources for an explanation, but...
View Articlechange in speed and wavelength of light while travelling from one med
what is the mechanism by which light changes its speed and wavelength while travelling from one medium to other. I know it is c/n or lamda/n and know it comes from maxwells equations, but what is the...
View ArticleChange in momentum when a body is thrown up and falls back down.
Say, a body of mass 'm' is thrown at a certain angle with the vertical with certain initial velocity 'u'. The initial momentum of this object is mu. Am I right to say that if it spent 't' seconds in...
View Articlesimple gravity question
hey all! can anyone please explain where the equation [itex]{Gmm_e}/{r^2}={mgR^2/r^2}[/itex] comes from given $$ma=Gmm_e/r^2$$ where [itex]G,m,m_e[/itex] are the universal gravity constant, mass of...
View ArticleConfusion in Electro Statics
During electrostatic induction,a posivitiely charged body is brought near to a uncharged body.During this uncharged body gets bound negative change toward the end of the body near to charged body. My...
View ArticleUltracapacitor to power electromagnet?
I have been looking for a better way to power my electromagnet than a bunch of AA batteries, and am now thinking of using ultracapacitors. I have a few questions. I have been looking on ebay for them,...
View ArticleHarmonic oscillation problem -Dancing pot
http://youtu.be/FZiBezCMUck Can anyone help to explain what is going on here? What are all the variables that might influence the frequency of this oscillation? Thanks
View ArticleEnthalpy of reaction
Given some chemical reaction, A+B -> C+D (all are ideal gases) that occures in 298K and 1 atm. why can't I automatically say that ΔH=0 for this reaction? I know that enthalpy is a state function...
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Magnetic field and repulsion bewteen wires
If you place a wire with a running current in a magnetic field, the magnetic field will excert a force on the wire. So, if you place two wires parallel to each other, the current on each will produce a...
View ArticleWhat do YOU think the most important FirstYear Phys topic is?
I'm kind of rushing through first year physics cause im doing it self paced, but I am realizing now that as an engineering i relaly need to internalize and fully understand these lessons. I don't have...
View ArticleStatic Equilibrium and D'Alembert's Principle
Virtual work principle states: [tex] δW = \sum^{N}_{i=1}\vec{F}_{i}\centerdot δ\vec{r}_{i}[/tex] And from this, we can see that if a system is to be in equilibrium we have [tex]δW =...
View ArticleMagnetic Energy of Solenoid With/Without Core
I have a question about solenoids. The formula for the magnetic field energy density is: [itex]\frac{1}{2}\frac{B^{2}}{μ}[/itex] If I have an air-filled core, then μ=μ0. If I have a steel core, then μ...
View ArticleElementary questions relating to Newton's laws of motion
i) If a wall breaks when it gets hit by a cannonball, did the wall exert an equal and opposite force on the cannonball? ii) Would the force exerted by the cannonball on the wall only be the amount that...
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