Original focal length: 1370 mm

Original primary aperture 150 mm

Is it as simple as 1370/24=57? Just treat the hole like...

F-ratio for certain setup?]]>

I may be purchasing a BenQ PU9730 (http://www.benq.com.au/product/projector/pu9730/specifications/) for use in a large venue, projecting an image 3 x 5.3 metres. The projection booth is 18m from...

How does changing projector lenses affect brightness?]]>

I was reading about drag, and didn't quite find what I was looking for.

A general drag equation is : 0,5 x ρ x u² x Cd x A, where there are some drag coefficients that have been found during laboratory experiments.

Let's say a sphere with a radius of 1m is traveling at 2m/s under...

Drag in water - object in a tunnel/tube]]>

Will that aircraft provide accurate moon trajectory?]]>

CAN THE PLANE TAKE OFF?]]>

A Question about Sound Waves Propagating Through a Large Metal Cube]]>

I have a 3.2m platform which weighs 175Kg. One end of the platform is touching the floor but the other end is on a pivoting bolt 2.5m in the air.

I need to figure out what the "load" would be on the end which is on the floor when I try to lift that end 4.5m in the air. Basically so I can...

The load of an object on a pivot]]>

Here is a short excerpt:

"Cracking like lightning through the void, all the specks of electrons and the specks of nuclei are constantly...

How does force transfer through an object microscopically?]]>

My question is 'Are these properties of water molecules totally new or were these properties already lurking around in the oxygen and hydrogen atoms?'

Thanks.]]>

I have recently done an experiment testing the effect of temperature on magnetism through measurement of magnetic flux at a constant distance away from the measuring device. I used a range of 0-90 C for neodymium and bar magnets, and found a reasonably linear trend, with a similar...

Magnetic Flux vs Temperature Relationship in Ferromagnets.]]>

When a magnetic field is applied across the left part of the tube , it's level rises as shown .

I would be grateful if someone could help me understand why this happens .

Thanks .]]>

I am wondering if suction power from a vacuum for example that has a set amount of power, is increased or decreased depending on the size of pipe. Does a large pipe decease/ increase the suction power, or does a small pipe decease/ increase the suction power? Is there a link to the size in...

Suction Through Small & Large Pipes]]>

8700 kgm2 * 1.83 rad/sec= 15979.6 Nm?]]>

Nonuniform magnetic field and stationary conductor]]>

Q1:

I was reading about ultraviolet catastrophe and it was said that atoms were assumed to be harmonic oscillators of radiation.

I believe that two harmonic oscillators could have the same frequency but different amplitudes so it would mean that two different atoms (i.e. two harmonic...

atom as a harmonic oscillator of radition]]>

Can we produce magnetic field from stationary charge?]]>

Please have a look on the attachment. Suppose that a 0.1 kg rubber ball having velocity of 60 m/s is moving between two walls A and B, and the distance between the walls is 1 m. It is having elastic collisions with the walls.

Let's focus on what is happening at wall B. The ball is moving...

pressure exerted by an ideal gas]]>

Q)When a current is passed through a conductor, will it be charged?

A)

Electric Current]]>

I will list as many details as I have in hopes that someone will know how to calculate the amount of sag I will have and tension/force there will be.

I am suspending a 1/8 steel cable horizontally...

Calculating amount of sag and tension for 1/8 steel cable]]>

I will like to check if I need to balance an out of balance shaft, why is the minimum number of mass block = 1

Is it because i can place the mass on the opposite end of the unbalanced mass at the same distance r away from the axis?

and how many are required to dynamically balance the...

Balancing of Rotating Masses]]>

Direction of the induced current]]>

Can 2 spheres orbit each other say inside ISS?]]>

Lower microwave absorption efficiency to increase penetration (cooking)]]>

Please see the page of the textbook attached .

There is a circuit consisting of an inductor , a series resistance (not shown) and a battery ( not shown...

Induced current in an inductor]]>

Large deformation in solid mechanics]]>

I originally thought tank K because the area in tank J is much larger than the area in the pipe connecting J to I

But then I realize Bernoulli's equation does not include volume but only includes height.

H_1, H_2 = height of water tank J, height of water in pipe...

Which tank fills first]]>

Let's consider a person with 100.000 Ω resistance. If V = R⋅I, then V = 0.06 A ⋅ 100.000 Ω = 6000 V, and that would be the...

Lethal voltage/current]]>

However an educationally useful...

Measuring gravity]]>

Here is the set up: Car A is travelling West at 5 mph. Car B is travelling South at X mph. Car B strikes A on the rear quarter panel (centered on the rear...

Calculating Speed at Time of Collision]]>

Geometry of magnetic fields]]>

Objects smaller with distance (again)]]>

If higher temperature is correlated with shorter emitting wavelengths, how come there are incandescent light bulbs that emit yellowish light but are hotter than incandescent...

Emission spectra of different materials]]>

The normal force is classically referred as

Does the normal force really equal mg on earth? I think not...]]>

Acceleration = dv/dt = -s/t^2 ?]]>

I was looking over my notes and I was trying to figure out when we integrate Q enclosed when Q = ρ*d(volume).

If there's one thing I've learned from physics II you only integrate when a field is non-uniform. I'm just wondering how we know when it's uniform (usually the problem will tell...

When to Integrate Charge Enclosed for Gaussian Surfaces?]]>

What is heat?]]>

I do apologize in advance for any errors or misunderstandings in my question, been that english is not my native language.

I was wondering how to calculate the RPM of a gear (or a wheel) applied with a known force. I'm guessing I'm not using the correct terminologies using Google,...

RPM of gear with a force]]>

Classical electromagnetic theory]]>

Question about the Photon]]>

I'm having trouble understanding this problem that was on an AP Physics 1 sample questions page:

View attachment 208956

So a couple of questions here:

(By the way, I know the answer is C)

1. My teacher explained that the net torque here on the assembly would be zero(will...

Rotation problem - AP Physics 1]]>

I = (mL**2)/3 for a uniform rod

in...

Calculate the power generated by a rotating rod turning a generator]]>

Suppose there is a 1 m

The average...

Joule Thomson effect etc.]]>

I have a list of measured temperature values of Venus at altitudes from several missions to the planet. This temperature is a combination of outgoing thermal emission from the planet, incoming thermal emission from the sun and any chemical reactions going on in the atmosphere.

Can I use...

Venus' temperature, radiation values and altitude]]>

1. How much role does weight, and or distribution of weight play a role in success over strength. For example, the...

physics of legwrestling and Mas wrestling]]>

Reference...

Why centrifuges on Earth and in space would be the same?]]>

Can you? (Exchange of (virtual) photons only explains repulsion.) An electrical field is playing hide and seek.]]>

Why does red food coloring look green when it dries?]]>

If two lasers cross over, do tehy ionisate eachother. If i have sensor in laser measuring ionisation going out etc can it see that laser 2 is crossing over it?

]]>

The Earth has zero net charge, so the work done in bringing any charge from infinity till the Earth is zero.

So what do statements like, "The potential of this...

Meaning of potential with respect to Earth]]>

Theorem behind Archimedes principle of buoyancy?]]>

Use of a half wave plate plus polarizer to attenuate lasers?]]>

https://en.m.wikipedia.org/wiki/Relativistic_electromagnetism

seems (to me) imply that there is always a frame of reference in which a magnetic field can be rather viewed as an electric field modified by relativistic considerations. Is that always true? That...

Magnetic field = electric field in some reference frame?]]>

Dipoles vs induced dipoles]]>

Also, if you could, could you...

What are the difference between electrical current and RF?]]>

∫E⋅da=Q/ε

E*4π*r^2=q/ε

E=q/(4*πε) in the r-hat direction

But im confusing about setting up the integral to get the same result

I tried

∫ 0 to pi ∫0 to 2pi...

Gauss's law of sphere using integral]]>

Lustre of metals]]>

I am doing this question where it asks if I increase the tension of a two loop standing wave without changing the frequency, what kind of standing wave will I get? I came to the conclusion that it would become a one loop standing wave as f= 2L/(n) as I plugged in 2 for n and I got...

Loops of a standing wave]]>

I'm working on a (private) Software Project and Part of that is finding a Way to Predict Projectile Positions. My thought's are explained from a Code View a little bit, but I tried to clarify everything so everyone could understand what's going on.

(It's my first time in this Forum, I...

Projectile Prediction with Acceleration & Delay]]>

Can someone help me find a method to measure water level in a tank]]>

Neutral wire in electric power distribution between substations]]>

View attachment 208897

View attachment 208898

Here, while calculating F, in eqn. 4.61 , Griffith doesn't bother about energy stored in fringing field.

So, even if I assume that there is no fringing...

Forces on dielectrics]]>

But what about AC?...

Movement of electrons in AC]]>

So the EM...

Charge at constant velocity emitting EM waves?]]>

accuracy of moon orbiting earth in how many days and hours and seconds and if it is multiplied by 14 how much it will be in days.

i need accurate answer.

Thanks,

Ahmed.]]>

Drone Gun]]>

Following the definition of dielectrics given in Griffiths:

View attachment 208862

The electric field inside the sphere,

## \vec E = \frac {-P}{3 \epsilon_0} ##

So, ## \vec P ≠ ε_0 χ_e...

uniform polarization and linear dielectrics]]>

[tex]P=mg/A=ρVg/A[/tex]

I understand it, but the problem I have is cancelling the area with the volume to give the height. How does this work when the volume of the liquid in the cone is...

Liquid pressure in a cone]]>

i am looking for a general form of a wave equation in a medium. i am not looking for a concrete physical equation but rather a generalized form (preferably in n dimension) of such under the simplest assumptions (it's of course a little equivocal what 'simplest' means but, well).

so for a...

Wave equations in a medium]]>

I know this is a really simple question, but I'm just making sure I have this concept down:

Scenario 1. An elevator accelerates down at 9.8m/s^2.

Scenario 2. The elevator cable is cut.

If someone is inside an elevator, scenarios 1 and 2 would feel exactly the same to them, correct?...

Elevator free fall]]>

Here is a miniature example of the type of parabolic circulated water heating devices I have been building.

My first questions would be what is the potential...

Solar Thermal Optics - Concentrated Light]]>

Quiz Question -- What happens to the cork?]]>

If this was the case would surface roughness still present an orthogonal area upon which the kinetic energy of the fluid would interact causing a...

No Slip condition in an Inviscid Fluid]]>

I am trying to improve my understanding regarding spectrometers bandpass, resolution etc. For that, I went through the Ridchardson grating handbook and on Horiba’s website where they have a nice explanation...

Spectrometer: bandpass and resolution]]>

Then if i took a 4th truck and hooked it to the back of truck 3 facing the opposite direction. Almost like tug of...

Hauling/Pulling Question]]>

In an experiment, I obtained the number 227.6 T.

Is this a sensible value for a small (5cm long) bar magnet? Thank you~]]>

I wonder what pressure is when there are no walls.

The reason for me wondering this is that gas pressure actually is defined by change of particle momentum, like

[tex]p=\frac{F}{S}=\frac{1}{S}\frac{dp}{dt}=\frac{1}{S}\frac{d2mv}{dt}[/tex]

So how can there be pressure without change of...

What is pressure when there are no container walls?]]>

View attachment 208620

And here's the exact same fin with the flutes cut out from all around the edges, allowing the edges to be squeezed shut and sealed with tape:...

Intuitively, which of these coroplast fins has less drag?]]>

Thanks in...

Time for Hot Water to Cool -- Calculation...]]>

Is there a unity across scale in the universe?]]>