Really Smart Cobras

Spitting cobras attack tactics presented a challenge to researchers. The cobras strikes are extremely accurate and each strike is unique. This is puzzling because the cobra's fangs are fixed so pattern of the fluid should be fixed. Also, the snakes 'wiggled' their heads just before firing.

The study, in the Journal of Experimental Biology, concludes that spitting cobras initially track their victim's movement and actually spit venom according to where they calculate the victim will be 200ms in the future.

Here's a video of the spitting cobra measuring up its opponent and striking.

Science Behind Traffic Jams

In high density traffic, small disturbances like braking too hard or getting too close to another car can quickly amplify into a traffic jam. MIT research is explaining why.

The mathematics of traffic jams are strikingly similar to the equations used to describe fluid mechanics, i.e. traffic acts a lot like fluids. Fluids flow as one unit and bunch up when the pathway becomes restricted.

Variables such as traffic speed and density help calculate when a jam will form and how fast it will spread. Once formed, there's nothing you can do except wait. So the plan is to design roads with enough capacity to keep traffic density low.

Physics of Surfing

How do surfers ride big ocean waves?

1) Ocean waves are a form of mechanical waves. Mechanical waves are disturbances traveling through space and time which jump from one particle of the medium (in this case water) to another ... so mechanical waves move energy, not physical substance. Wind causes ocean waves travel along the surface of water. Slope and width of ocean bed and wind speed, duration, and size all effect ocean waves size.

2)OK, so now that we know what ocean waves are, how do you surf them? Newton's 1st law states that, minus an outside force, objects in motion (e.g. waves) stay in motion and objects at rest (e.g. surfboards) stay at rest. Newton's 3rd law states every action has an equal and opposite reaction. As waves rise, they reach a point where they cannot sustain themselves and begin to collapse. This point of collapse is known as the wave's "break". Surfers exploit the break, pushing down on the board as the wave pushes up on the board. The board does not sink because the ocean water is denser than the surfboard. Also, water surface tension (the force which allows water to stick together and form droplets instead of spread out) is very strong and helps push the board up. All that's left is for the surfer to maintain their center of gravity, much like one does when riding a bicycle.


Now that you know all that, see if this doesn't seem to defy wave physics.