Tag Archives: collisions

New toys in the puzzle maker!

Valve released some new items for the educational build of the Puzzle Maker! Here’s a rehash of some older videos about momentum and collisions using the new toys.

Bonus feature! Check out this crazy oscillator device I made with contraption cubes of different masses. It’s pretty mesmerizing. The cubes get heavier from left to right but the strength of each aerial faith plate is the same.

Here’s a quick high school physics lesson.

My oscillator reminds me of the wave pendulum in the video below because both systems show repeating patterns. The swinging billiard balls form a wave with varying frequency. My oscillator also appears to be demonstrating wave-like properties.

The billiard ball pendula are oscillating on strings of varying lengths but are pulled to the same angle. The period (time of one oscillation) of a pendulum pulled back to a small angle is

Period = 2Π√(length/strength of gravity)

So, if you increase the length of the pendulum, you increase the period. Each progressively longer pendulum takes a bit more time to make one period in the same way that each progressively lighter companion cube stays in the air a bit longer. Of course, the game’s oscillations aren’t perfect. I’ll take another look at the differences between the way the cubes are bouncing and how they should bounce to determine the exact variations between the physics of aerial faith plates in the game and similar launchers in real life.

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conservation of momentum and collisions

Do mass and velocity play a role in the outcome of collisions? Let’s find out.

We’ll be colliding three objects: a cube, a sphere, and a turret. A cube has a mass of 40 kg, a sphere has a mass of 75 kg, and a turret has a mass of 100 kg (found by using the console command physics_debug_entity while looking at an object). If all goes well, the object with the larger momentum due to its larger mass or greater velocity should send the other object flying backwards as the result of their collision.

Test 1: Two cubes of the same mass hitting at the same velocity.

Their identical momenta cancel out.

Test 2: A sphere striking a lighter cube at the same velocity.

The sphere’s larger momentum causes the cube to fly backwards.

Test 3: A cube striking a turret.

The turret has a larger mass and its momentum causes the cube to fly backwards.

Test 4: A sphere striking a turret.

The turret has a slightly larger mass and its momentum causes the cube to fly backwards.

Test 5: A fast cube strikes a slower cube.

The fast cube’s greater momentum knocks the slower cube backwards.

It looks like mass and velocity are significant factors in collisions and handled correctly (at least superficially) by the Source engine.

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