2008 March | Talk Like A Physicist

Mar 30, 2008

Motionless Monday : Spherical shock waves of gun firing

This full-scale Schlieren image shows the discharge of a .44 Magnum revolver.

The basic optical Schlieren system uses light from a single collimated source shining on a target object. Variations in refractive index caused by density gradients in the fluid distort the collimated light beam. This distortion creates a spatial variation in the intensity of the light, which can be visualized directly with a system designed to capture shadows.

Two spherical shock waves are seen, one centered about the gun’s muzzle (the muzzle blast) and a second centered on the cylinder.

The supersonic bullet is visible at the far left.

Source

Update:

Penn State Gas Dynamics Lab seems to have generated this image. Normally I would link to the lab, but it hasn’t been updated in a while. However, You can see some spectacular Schlieren image images taken by Gary Settles of Penn State in the NY Times article: Mysterious Cough, caught on film. Talk Like a Physicist

Mar 28, 2008

Posted by Sunny Kalara | 0 Comments

Physics Embroidery : Law of Gravity

physics_embroidary

Source

Talk Like a Physicist

Mar 28, 2008

Posted by Sunny Kalara | 5 Comments

Common physics errors in science fiction movies

Here are some of the most common physics errors in SF movies:

There’s no sound in space – next time I hear an explosion when a spaceship breaks apart, I am calling the physics police. Also, sound and light don’t travel at the same speed and can’t arrive at the same time!
There are no fires in space – even if you provided oxygen, the vacuum of the space will dissipate it all so fast! No flaming things in the space please.
You can’t see a laser beam in space. You see the laser beam on earth because of the reflections from the dust particles.
And there’s no reason why someone would move in slow-motion in zero gravity; in fact, they should be moving around much faster. Stop showing those goofy slo-mo movies.