A car driver going at some speed 'v' suddenly finds a wide wall at a distance...
Should the driver apply brakes or turn the car in a circle of radius 'r' to avoid hitting the wall? This question is in the excercise of circular motion chapter. In this question I don't uderstand from...
View ArticleCalculating Insulation Thickness
I'm trying to calculate insulation thickness for a foundry, and can't figure it out after spending a few hours searching. Refractory: Kast-O-Lite Material Required: 1.44g/cm^3 Thermal Conductivity:...
View ArticleDesign electromagnet in pipeline
Hi, I wanted to create electromagnet around pipeline to produce 0.2 Tesla magnetic field. How can it be connected to the DC from 220 Volt.. Please help me..
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Elasticity problem
Hello, I am struggling with this problem. It is probably the easiest problem ever... What I did: The plane has 2 stress components. σn and σs. σn is a multiple of (l, m, k) vector. For σs, I made up a...
View ArticleCalculating Reflection angle in a 2D plane.
Im trying to calculate the refelction angle of 2 points in a 2d plane, but not the same distance away from the reflection surface, and I'm drawing a blank. Any help would be hugely appreciated.
View ArticleMeasuring the permeability of metallic objects
Hello everyone. I'm working on a project where I have to do a finite element simulation of low frequency magnetic coupling. But my problem is that I don't know the permeability of all the objects...
View Articlecircular motion
how can rcosθ in a banked road be equal to mg; since r is equal to normal reaction which is equal to mgcosθ. rcos is even smaller than r. so mg>mgcosθ mgcosθ=r r>rcosθ so mg>rcosθ then how can...
View ArticleHow Can A High-Torque Motor Have Low a low RPM
Torque is the rotational force. If there is more force, how can the motor be slow? I'm building a DC motor and read that given a constant amount of coil, creating a very dense coil will increase torque...
View ArticleElectric Field vs Electromagnetic Field
If we have a static electric charge, it generates an electric field. If that static electric charge is accelerating, it generates an electromagnetic field. What about if the electric charge is moving...
View ArticleThrottling Ideal Gas
A quick question about throttling: I've read that for an ideal gas, if you force it through a capillary into a vacuum and allow it to equilibrate, it will experience no temperature change. I was...
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Stress in a beam
if you look at the attached photo. we have 2 beams, 1) is shorter, 2) is longer. cross-sectional area is the same. same force is applied X cm from the fixed end. what is the max stress in each case?...
View ArticleTds Equation and Entropy
Hello I was wondering, with regards to the Tds equation Tds = de + pdv: 1. All of my textbooks state that integrating this equation, although derived for a reversible process, will give the entropy...
View ArticleProjectile motion range
Can anyone explain to me why (when air resistance is ignored), that 45° angle is the ideal angle for the longest range? Is it because if it is over 45° then gravity will be acting on it longer...
View ArticleHelp understanding a physics inertia experiment(Hammer and a heavy block)
The experiment is the following: First part - The demonstrator puts an egg in the table, and places a heavy block resting above the egg, then he applies a force in the heavy block using the hammer, and...
View ArticleIf entropy is a state function, how can it keep on increasing?
I just have this confusion which is completely eating me up. They say entropy of a system is a state property. Then they say that for a completely isolated system, entropy either increases or remains...
View ArticleUnderstanding Work Done
I have always managed to solve problem asking how much work is being done but then once I start to think about the work being done I get confused. E.g A barrel of weight 200N is raised by a vertical...
View ArticleLegendre Transform of Entropy
Trying an example from a textbook but I don't understand Legendre transform at all. "construct Legendre transforms of the entropy that are natural functions of (1/T, V, n) and (1/T, V, μ/T)". I don't...
View Articlerolling & slipping
hi pf, the more i think i have understood classical rotational mechanics the more it turns out to be clumsy? i am just not able to understand the slipping and rolling of bodies? somewhere friction...
View ArticleRegarding transmission and reflection of EM-waves
Hello! I´m trying to read Jacksons 'Classical Electrodynamics' and solving some problems. At the moment I´m stuck at problem 7.3. I started looking at suggested solutions...
View Articleon weight of photon
hi pf, my friends asked me a strange question to me today, "if in a vacuum chamber if light is somehow focused on a suitable weighing machine then will there be any deflection? if yes does that mean...
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