MORE PHYSICS!!!

I continued on my physics unit today, and learned about Isaac Newton. He is the man credited with discovering the relation between mass and inertia, acceleration, and three laws of motion.

Today, I did three experiments, all related to his laws of motion. The first one explained that "The change in motion of a body is proportional to the strength and direction of the applied force", which is Newton's second law of motion.

First, I attached a bungee cord to a cup, and measured how long the bungee cord stretched.

It was 5 1/4 inches. Next, I added 25 ml of water. The bungee cord extended to 5 3/8 inches. I added 25 more m of water. The bungee cord extended to 5 1/2 inches. Finally, I added another 50 ml, totalling 100 ml of water. The bungee cord measured 6 inches, 3/4 inches longer then it started.

This simple experiment proves that the more force that is applied to an object, the greater the force of the reaction will be.

You can see some pictures of it below. (You can't really tell the difference between them, but when I measured it, there was definitely a change in the bungee cord.)

For my second experiment, I did one that showed friction in action, and how it interacts with other forces. Newton's first law of motion states "A body persists its state of rest or of uniform motion unless acted upon by an external unbalanced force." For the experiment I conducted today, I first took a coin and put it on a piece of paper. Next, I placed the paper over a cup so the coin was directly above the opening, but on top of the paper. If I pulled the paper slowly, the coin would move with it. However, if I jerked it quickly, then the coin would stay in place, and fall into the cup. I took a video of it, which I have posted below.

When I pull the paper slowly, the friction in between the coin and the paper is greater than the coin's inertia, which results in the coin moving along with the paper. However, when I pull the paper quickly, the force of me pulling the paper is greater than the force of the friction, and the coin stays where it was, dropping into the cup. This is proving Newton's first law of motion.

You can learn more about this here.

For my third and final experiment, I conducted a very interesting one. It involved Newton's third law of motion, which is "To every action there is an equal and opposite reaction."

There is an interesting invention, called Newton's Cradle, which demonstrate's this law. It works because the force of one ball striking the group is enough to move a ball equal to it's own weight. Also, the force of two balls is enough to move two balls, equal to their own weight, and so on and so forth.

I made a simple version of this, involving marbles and a box. You can see a video of a large Cradle below.

Physics!!!!

Today, I started a new unit in my science projects. Now, I'm learning about force and the way it acts on objects. I did a very simple experiment today on friction. Friction is a force that acts in the opposition to the force of motion, and thus acts like a brake on movement. The following experiment shows how friction can be reduced.

First, I wrapped a rubber band around a book, and attached a bungee cord to it. I then measured the length of the bungee cord with no tension on it. It was 11 in. Then, I stretched the bungee cord until the book began to move. I measured how far this was. This measurement was 16 inches. Next, I put down skewers on the table, and put the book on top of that. This time, when I dragged the book, the bungee cord did not stretch at all, and it was much easier to move the book. This works because the friction in between the book and the skewers is significantly less then the friction between the book and the table.

This method was used by the Egyptians to contruct buildings, especially the pyramids.

You can see a picture of it below.

For my second experiment, I investigated Galileo's Law of Falling Bodies. People used to believe that objects fall at a constant rate, in relation to their weight. Galileo proved, however, that objects accelerate, and their speed has nothing to do with their weight. He used an inclined plane to prove this, and I did a similar experiment. I put some books under one end of a coffee table, to give it a slant, then taped down some pieces of string about 20 CM apart. Next, I rolled a marble down the table, across the strings. You could hear it clicking as it bumped over each string. The interesting thing is, the clicks became close and closer together. This proves that the marble is accelerating. I recorded this sound, and I have posted an image of the waveform below.

You can see that each click getting closer and closer together. Also, I have uploaded a picture of the whole setup below.

The second part to this experiment was to try to set the strings the right distance apart so the marble made a consistant clicking sound.

I uploaded the waveform of this experiment, and the picture of the sting setup, as well.

Magnetism

Today for science, I learned about magnetism, and it's relation to electricity. I also built some pretty awesome experiments, which I'm going to write about now.

The first one I made was a simple experiment about how magnetic fields could be created with electricity. A guy named Hans Christian Oersted is credited with inventing it. Basically, I am turning a wire into an electromagnet, which the compass is attracted to. You can see a video of it below.

My second experiment was creating a Galvanometer.

This is essentially a device that detects electricity. I made this by wrapping over 2 meters of wire around a compass. When a charge was applied, the needle would swing violently to one side. You can see some pictures of it below.

My third and final experiment was creating a model based off of an experiment of Michael Faraday. I wound a LOT of wire around a bar magnet, and then applied a charge to it.  A nearby compass would swing around and point at it. I had created my own electromagnet. My electromagnet behaves just like a regular one, but I can switch it on and off like a light. You can see a few pictures of it below.