Rube Goldberg Physics

This post is looking to clarify some information from our last post, and discuss some more of the physics behind our machine.

Firstly, forces do not transfer from one object to another. Force= Mass x Acceleration. Therefore force is directly dependent on an objects mass and acceleration. if the acceleration increases the force increases.

Or dominoes are a good example for most of the physics we need to understand, and are as close to ideal as most objects come. While dominoes are stationary the the forces acting on each domino is equal.

Dominoes have inertia, so they obey Newton's fist law of motion. (an object at rest or in motion will remain as such unless acted upon by an outside force.) Inertia is an objects resistance to being moved. The smaller the mass of an object the less inertia it has. Since the dominoes have minimal mass there inertia is small, therefore, they can easily be forced into motion.

In the case of our first set of dominoes our ruler/candle hammer knocks the first domino and causes it to accelerate from its stationary position. When this domino accelerates it transfers its momentum to the next domino; this process continues through the series of dominoes.

Dominoes also can help explain Newton's second law of motion which states that Force= Mass x Acceleration.  The greater the mass of an object the more it resists acceleration, yet the more force an object has the more it is accelerating. Our dominoes have a small force because they have a small mass, since the mass is small and the force acting on the first domino is small the acceleration is not as great.

Dominoes are also a good example of Newtons third law. For every action there is an equal and opposite reaction. Dominoes exhibit this when they fall over. When one domino falls over it knocks another one over. The domino can knock another domino over because they have the same mass; therefore the reaction is equal. The action in this case is a domino falling: for every action (the domino falling) there is an equal (The next domino falling) and opposite reaction (is the force that is being pushed back on the fallen domino).

Speed is the distance over time. How fast an object moves over a span of time. Our Rube Goldberg  machine over its entirety has speed as do each separate step. The easiest way to see this is in our first step. When the car travels down the ramp. The speed is how much distance (the length of the ramp) is covered over time (how long it takes the car to reach the bottom of the ramp).  The car in this section also exhibits acceleration. Our car can also be used to describe velocity. velocity is a speed in a given direction. Since our car is traveling forward in a set direction it exhibits a forward velocity. The given average velocity of our car would be measured by taking into account the speed of the entire trip and averaging it. This mans average velocity takes into account many instantaneous velocities (which are an objects velocity at any given time).

Acceleration is what occurs when an objects velocity changes. in the case of our car the velocity is going from being less to more from the top of the ramp; this means the car is accelerating.

Momentum is an objects mass times its velocity. Momentum and acceleration are related in that they acceleration is dependent on an objects momentum.

Potential energy is equal to mass x gravity x height of an object. Potential energy is highest at higher points. For example the point with the highest potential energy in our machine is the ramp that the car accelerates down. At the top of the ramp the car has the highest potential energy, and the bottom of the ramp this energy is converted into kinetic energy. Kinetic energy is 1/2 mass time velocity squared.

Rube Goldberg Success!

Where are we?

On Wednesday we were able to complete our rube Goldberg machine after tons of attempts with no success. This was extremely gratifying, and a huge relief. Below is the video of our completed machine.

Forces


We had many forces at work in our machine, the most used was the forces found in dominoes. Dominoes like all other objects obey Newtons first law of motion: an object in rest, or motion will remain in its state unless acted upon by an outside force. The dominoes stayed where they were until they were hit by the third step of our machine. This caused one domino to fall over and hit another, this process continued until all the dominoes were knocked over. The force that was gained by the first domino being hit by the candle/ruler was transferred to the other dominoes when they were hit. This was not the only force that acted upon the dominoes seeing as each had its own potential energy. As the dominoes fell momentum was also gained throughout the process. Dominoes falling is commonly referred to as the domino affect.

Hardwood Model.

We used the Harwood model of inquiry throughout the making of our rube Goldberg

During our initial proposal we defined our problem: Turning on a speaker using a series of steps.

We began looking for ideas by watching Youtube videos and pictures of other rube Goldberg machine

We started by picking a fist step: a moustrap that ignited a match. Needless to say that idea did not work out so well as a first step, or a step in general. We tweaked the idea and ended up with a different second step, that still involved a moustrap and accomplished what we originally Intended. This was one example of making observations and communication.  We actively changed our steps when we realized they weren't working. We talked about the problems and discussed ways to change them. Our rube Goldberg machine was a collection of ideas from each person in the groups and illustrated collaborative interaction.

                

Our process resembled the Hardwood model rather than a linear model of inquiry, because it   was in constant flux and we were constantly jumping from one process to another depending on what step we were doing, or if we were trying to figure out how to get from one stept to another.

                

This type of expierment is good practice for building patience and practicing problem solving. Though there is not real applicale use for a rube goldberg machine they are fun to build. 

Rube Goldberg Update part two

Things have been going according to plan... well an adjusted plan. I hate to say it but we ended up having to scratch the match-lighting mousetrap invention that we started using. This idea was just too unreliable; whoever thought "green" matches were a good idea should be publicly discredited, but despite the matches the overall design was not reliable enough to be a focal point in our machine. We actually adjusted our second step to include a mousetrap device reminiscent of medieval torture machines. Featured below is this machine.

If you look closely you can aptly observe the razor blade ductaped to the mousetrap. This devise, besides taking off fingers, serves to cut the piece of string that is holding the ruler in place.

The ruler then falls setting off the dominoes, which in turn bumps a group of marbles.

The marbles fall into a funnel that directs them into a cup.

The cup is attached to a piece of paper that is held down by a second set of dominoes. The cup (which is attached to the paper with a sting) falls pulling the string through the pulley mechanism, this pulls the paper out from under the dominoes triggering them to fall.

This whole process can be seen in the following video. I have slowed it down just a smidge so the steps can be more easily seen.

We also figured out how we were going to get our speaker to play, which had been giving us some major issues. we were able to figure it out because Mel Strong (the 263 teacher) let us barrow a converter that tweaks the frequency of the sound waves being produced.

We are still in the process of figuring out all of the steps that will make it possible for us to get from our sixth step (the second set of dominoes) to the step that turns the speaker on.

All in all, I fell that our project is coming along frustratingly, but well.