Battery LIfe

Although the terms are similar, electric potential and electric potential energy are not the same. While energy is measured in joules, volts are the units of electric potential. Also, electric potential is the amount of potential energy, or work, for each charge. Like other changes in energy, electric potential energy is based on force and displacement. This photograph contains different types of batteries. Although batteries may have different sizes, the amount of potential energy per charge can the same for all of them. However, the size of the battery determines how long it lives. Smaller batteries do not last as long as larger ones with the same voltage because a larger battery can keep more potential energy.

Electric Forces

Similar to how matter and momentum are conserved, the net charge of an isolated system will also remain constant. This picture shows two spheres with a cord between them. This is meant to serve as a model of a system involving metal spheres. If the sphere on the left has a charge of +4 C and the one on the right has one of -2 C, the electric force would be 8 N attractive since they are unlike charges. The total charge of the system is 2 C, the sum of 4 and -2. If a wire connected them, each of their charges would become the same. Since the total charge is 2 C, each would have 1 C for its charge. As a result, the force of the spheres would be 1 N repulsive since the charges are the alike.

Introducing Electricity

An electric charge causes a force between objects. Unlike momentum or acceleration, people cannot see electrically charged atoms with their own eyes, let alone the particles that compose them. The charge of an object is either positive or negative. This picture contains a fork and a cup. The fork is made out of metal, which is a conductor. Conductors are materials that transfer electrons easily because they want to give them up. This is characteristic of a positive charge. Meanwhile, the cup is created with glass, which is an insulator. Insulators do not transfer electrons easily because they want to take electrons, which is a quality of a negative charge.

First Semester Review

Overall, I found this semester of physics to be both difficult and enlightening. The equations used in physics definitely enforce mathematics, mostly algebra but also trigonometry when three-dimensional motion is involved. Since most of the physics units involved vector quantities, negative and positive values determine if the direction of an object remains the same. At times, I was not sure about how to work with certain ideas. Since I did not always understand the concepts of the unit, my ability to use them was often hindered. My most consistent problem during this semester involved confusing one definition with another. For instance, I would mistake acceleration with momentum, which made me incorrectly believe that momentum and acceleration would be conserved during a collision. In reality, when two unequally massive objects collide, they must have different accelerations in order to have the same force of impact.
Since Christmas is approaching, these pictures display a festively dressed dog perched near a staircase. One of the main principles of this course seems to be that even a mundane setting can highlight physics in some way. If the dog was pushed down the staircase's handrail, the dog will fall downwards because gravity forces objects in that direction. Since the rail lacks friction, it doesn't prevent the dog from moving. Also, as the dog travels, its potential energy turns into kinetic energy. In essence, physics is both basic and puzzling to those who are learning about it. Although physics can still perplex me, I do appreciate its relevance to the world. 

A Work Out

In physics, work is defined as a scalar quantity of an object's change in energy. Energy is directly related to force and displacement. As a result, it is measured in joules, which is the product of Newtons and meters. Like matter and momentum, energy is neither created nor destroyed in an isolated system. However, the energy can transform into other forms. In these blurry pictures, I bounced an exercise ball on the ground. The energy that I lost from bouncing the ball is equal to the energy gained by the ball. As the ball bounces, some of its initial energy turns into heat and sound, so the height of its bounce decreases as time continues.

Egg Drop

As a way to observe momentum, my classmates were divided into groups that had to drop eggs without breaking them as they landed on either the road or the sidewalk. In order to prevent the egg from being harmed, my group used three car sponges, a rubber band, and rope to enclose it. A hole was cut in the middle sponge as a place for the egg. On Wednesday, one of my group members dropped it from the designated area and I retrieved it from the road. A few moments later, I discovered that my group's egg survived its fall. Basically, the egg did not crack because its enclosure increased its contact time with the road. As a result, the average force on the egg decreased because the sponges absorbed some of the egg's force.

More Momentum Moments

 

Impulse often demonstrates the impact of a force on an object during a certain period of time based on the product of the object's mass and velocity, which is the definition of momentum. The average force on the object changes due to contact time. When an object falls straight to the ground, the contact time between them is small so the object feels a large amount of impact by the force. In order to reduce the amount of impact between the objects, the contact time between them must increase. In these two photographs, a bear falls on the floor and then on a pillow. Due to the pillow, the average force of the ground has less of an impact on the bear because the force distributes itself over a longer period of time.