Who isn't amused by the rare and impressive science-savvy party trick? One that involves the potential to risk death death by flinging yourself Superman-like at a bouncy training ball, only to have it pop you back up in an amazingly graceful backflip? Before you cry "Sir Isaac Newton!," here are the physics behind this seemingly impossible stunt.
Check out this demo reel of Levi Meeuwenberg doing some jaw-dropping "free running". Free running is very similar to Parkour in the athleticism required and specific techniques and movements used, but while Parkour is about getting from one place to another in as efficient a manner as possible, free running is less directed and more creative in nature.
As mentioned in that ancient post, when performing either of these activities, in addition to spending years developing a formidable set of technical skills, balance, physical strength, and kamikaze attitude, it's important to be cognizant of some basic physics.
Enter the two-handed bowler. Increasingly, we are seeing this novel technique cropping up in bowling alleys across the country. Notice the formidable hook you can generate with this type of delivery -- it looks like the ball is headed straight for the gutter, but then, seemingly at the last second, it cuts back into the pocket for another strike. It's this superior hooking ability that makes two-handed bowling a force to be reckoned with. In order to get some insight into the issue, let's examine some of the physics involved in tossing a 12- to 16-pound sphere down a lane of polished oily wood.
In order to get a strike you probably already know that the ball needs to strike the pins in one of the "pockets", which are the regions halfway between the head pin and the pins on either side of the head pin. But why do we need to hook the ball at all? Why not just throw it straight up the alley and directly into the pocket? The answer has to do with conservation of momentum.
For a beautiful demonstration of both magnetic force and gyroscopic motion, let's contemplate the Levitron. This novelty toy (which even now sits on my shelf waiting for a quick spin around the block) consists of a magnetic base upon which you spin a magnetic gyroscope. Both the bottom of the gyroscope and the top of the base contain magnetic north poles, and therefore they repel each other.
However, try as you might, you'll never be able to balance the magnet above the base without spinning the top. Why is this?
Ladies and gentlemen, for your consideration -- a real-life Rube Goldberg machine! As you may or may not be aware, Rube Goldberg was an early 20th century cartoonist (and engineer). His cartoons depicted imaginary machines capable of performing ordinary tasks in an extremely complicated way. Here in these modern times, we see the Rube Goldberg legacy in the children's game called "Mousetrap." In the educational arena, the building of Rube Goldberg machines has become a popular project in high school and college physics classes, and for hobbyists dabbling in this whimsical genre. Why? Because these contraptions beautifully illustrate a number of fundamental physics principles.
A few weeks back we analyzed some of the features of the innovative Newton Running shoe in terms of the relevant physics principles. While at the time the point was to assess the theory behind the shoes, it was suggested that I put them to the test in my "lab." In other words, out on the roads and trails where, being of the distance-runner species, I generally spend at least an hour per day. While this is in no way any kind of systematic scientific experiment (which is beyond the scope of my resources), based on my personal experience with the shoes, I'll make an informal attempt to further address the claims made by the two Newtons (Running and Isaac!).
It's physics demo day, and here we have the old "television picture distorted by a magnetic field" trick. Many of you may have observed this phenomenon directly, or even perpetrated this electromagnetic prank yourself. However, let's use the experiment to clarify some basic electromagnetic principles that are fundamental to the universe in which we live, as well as excellent for small talk at cocktail parties.
Behold a "hydro-car." You might see its like in the next James Bond movie; this real-life model could be useful for navigating urban waterways or during heavy flooding. Obviously, to propel your car through the water there must be some sort of propeller hidden under the chassis, but a more immediate and basic requirement is that your car must be able to float.
This video puts some perspective on the action-movie high-speed car chase jump phenomenon. Notice how close this car comes to wrecking when launched off of a little teeny two-foot-high ramp and moving at a relatively slow velocity.
In fact, just for fun, let's do a rough estimate of the takeoff velocity. We approximate that the car lands about 10 meters from its takeoff point and is in the air for close to one second. Applying this information we can do a simple calculation to determine its horizontal component of velocity on takeoff:
vx = Δx/ t = 10 m/1s = 10 m/s
Using a little vector addition we can also determine the net velocity off the ramp based on the ramp angle. We'll leave this as an exercise for anyone so inclined (no pun intended), but because the take off angle is pretty small (we estimated 17 degrees) the net velocity is still only approximately 10.5 m/s or 23 mi/hr -- not really a high-speed stunt.
Fun, games and calculations aside, one of many problems any "would-be" stunt car driver is going to face on attempting a jump, is that the car is generally going to follow the standard parabolic trajectory of a projectile.