Applied Physics Blog

### Questions

For homework tonight, I’d like you to take a look back on all of the simple machine activities we have done thus far. Look at terms like Mechanical Advantage, Work, Effort force, and distances. On your blog (since it’s been a while), ask a few questions about those experiences that you are still confused about! Those will help me to know where you stand. Good luck and see you tomorrow!

One activity that I am particularly confused about it the Ramps and Mechanical Advantage worksheet. I am having trouble understanding exactly how to apply mechanical advantage using the spring scales and ramps. Maybe it is due to the fact that my group had trouble understanding the project, but I remember that once it was explained to me I was able to understand it better. I think I just need to review this specific assignment.

For homework this weekend, do a little research about what a “simple machine is” (like 10 mins). Then, observe the world around you for the day. See how many you can find! Take some pictures Then, post these and write on your blog about what you found and how you think these machines make the tasks they are associated with easier (less effort etc.)

A simple machine is a mechanical device that changes the directions or magnitude of force. Some simple machines include levers, pulleys, inclined planes, wedges, screws, and wheel and axels.

Here are some examples:

This is an example of a pulley. This makes pulling your shades up or down easier because you do not have to pull or push the shades themselves. Since the top of the fabric for the shades is so high up, it would make it very difficult to control the shades if you did not have the pulley device. This simple machine is an example of a screw. This device was attached to a drawer’s handles. It makes things easier because it keeps the handle on the dresser securely, which makes it easier to open drawers.

These stairs are an example of a inclined plane, which is a form of a ramp. They make getting to different floors easier because it enables people to actually reach other floors. Getting up and down would otherwise be impossible (excluding elevators).

The knife is an example of a wedge. The thinness and sharpness of the knifes makes cutting easier and cleaner.

### Elasticity

post on your blog about the relative ELASTICITY of these two different balls. What makes them different? What do you think affects or changes their ability to deform and reform? What do you think this means in terms of energy transfer etc. Make some predictions!

Elasticity is defined as the ability of an object or material to resume its normal shape after being stretched or compressed; stretchiness. In both videos, the ball’s shape transforms. The first video of the bouncy ball seems to bounce and transform more quickly than the tennis ball. I think the material and the interior of the ball affects the two ball’s ability to deform and reform. Although the tennis ball solely encloses air and is made of rubber, the bouncy ball is completely made of rubber without any other materials to effect the bounce due to friction. I think the fuzziness of the outside of the tennis ball blocks or absorbs some of the energy from being transferred to the ground.

### Angry Birds Brainstorming

To being to brainstorm ideas, our group began to throw out ideas. Then we decided to each sketch out our own ideas of what to do. I though of using water balloons as the pigs, and nerf type of ball with pins sticking out as the bird. This would make the object of the game to aim the “bird” in a slingshot in order to dodge the obstacle, and pop the balloons. Another idea that most of us thought would be interesting to experiment with would be to create a type of potato shooter. This would enable us to control the air resistance and force of shooting the “bird” without human interference with a slingshot.

### Friction: Winner or Enemy

A time when friction is a winner is when it allows objects to slow down as they are being passed across a surface. In my activity group we sit around a big table with a bag of cookies in the middle. Friction allows us to pass the cookies around the table with enough force so that it slows as it gets to the receiver.

A time when friction is the enemy is when is slows down an object to a stop before it reaches its acquired destination. In the same scenario with the cookies being passed across the table, there often isn’t enough force applied to the bag of cookies to reach its receiver. Friction slows down the bag too soon and leaves it annoyingly unreachable in the middle of the table.

### The Law of Inertia

The Law of Inertia is Newton’s first law of motion. It states that an object at rest stays at rest and an object in motion stays in motion with the same speed and same direction unless acted upon by an outside force. This law occurs in my life on a daily basis involving my car. My car remains at rest all night until I (an outside force) take it out and drive it to school in the morning. My car stays at rest every night until I set it in motion every morning.

### Falling Object Comic

(click for enlargement)

### The Scale of the Universe

This site not only intrigued me, but completely blew my mind. It is amazing to see how insignificant we are in terms of mass and everything else within the universe. When I thought I could not go any bigger or smaller, I realized the scale was only slightly above or below the middle. Like, what’s a quark? And is everything really made of quantum foam?… I also felt especially interested in the planets and stars I had never heard of. I noticed that weight was only commented on within the earth’s objects. The gravitational pull on earth is the reason why so many minuscule objects are able to exist here. Other places, such as planets, stars, etc., were mostly mentioned in comparison to mass. The other aspects of the universe do not have many articles on their surface, and therefore do not usually comment on any kind of weight there.

### Hypothesis for the Washcloth/Water in Space Video

Since there is no gravity in space, the water would not disperse from the washcloth due to magnetic forces. In past years, I’ve learned that a positive and negative force creates a “sticky” effect; Since these forces are opposite, they act as a magnet and stick together. The H2O molecule has two positive charges (hydrogen atom) and one negative charge (oxygen atom). Since the water molecule is predominantly positive, the washcloth must predominantly be negative. Just because there is no gravity in space, doesn’t take away from the charges and makeup of particles. Rest assured, this is solely a hypothesis.

### ‘Simple Linear’ Motion

A simple linear motion I use daily is the walk from the gate to the cafeteria when I arrive at school. My position begins at the gate and I walk at a constant speed towards the cafeteria. Though my displacement is always the same, my distance sometimes varies based on people or things as obstacles. My velocity also remains the same as my speed is constant. Here are some rough sketches of how this ‘simple linear’ motion would look on a graph in velocity, position, and acceleration (educated guess):