CPO Sections 4-1 and 4-2 notes. MOTION

If you know how far an object traveled in a certain amount of time, you can determine the object's speed.

There are three types of speed; average, instantaneous, and constant. Average speed is calculated by dividing the total distance by the total time. For example, your family drove 300 miles to Chicago in 5 hours. The average speed is 60 miles per hour. But the car did not drive that speed the entire time. Instantaneous speed is speed calculated at one moment in the trip. Constant speed is speed that does not change.

Velocity is speed in a given direction. 10 miles per hour SOUTH. That added direction turns speed into velocity, but the two are mostly the same thing. The only time velocity can change, but speed remains constant, is if the object is moving in a circular path.

In a speed graph, the distance is on the Y-axis and the time is on the X-axis. A steeper line would indicate a faster rate of speed. This is called the slope.

In an acceleration graph, speed is on the Y-axis and time is on the X-axis.

CPO Notes 4-3. Acceleration and Free Fall

Acceleration is more than picking up speed. Acceleration is a change in velocity. A car is accelerating if it is going faster, slower, or changing direction.

If an object is losing velocity (slowing down), it is accelerating. This type of acceleration is known as negative acceleration or deceleration.

If an object is moving in a circular path, it too is accelerating. This is acceleration is due to a change of direction. Think of the carousel.

The common unit for acceleration is the meter per second per second. m/s² This means for every second the object is in motion, it is going that much faster or slower. For example, if an athlete is jogging at 5 m/s but is accelerating at 2 m/s/s or 2 m/s² . In three seconds, the pace would be 11 m/s. After 1 sec (7m/s), after 2 sec (9 m/s), after 3 sec (11m/s).

An object is in free fall is if gravity is the only force accelerating the object.

Gravity accelerates all objects at 9.8 meters per second squared.

CPO 16.1 Charge and electric circuits

To understand electricity, you must understand the atom. Atoms are the smallest particles of matter. Atoms have three sub-atomic particles; protons, neutrons, and electrons.

Protons have a positive charge (+), neutrons are neutral (n), and electrons are negative (-).

If all are equal, the atom is said to be electrically neutral.

A build up of electrons makes the object negatively charged, which is electricity. Think of the 3 E’s.

EXTRA ELECTRONS = ELECTRICITY

There are two types of electricity, static and current. Static electricity has no given direction or constant flow. It’s fun, but basically useless. Lightning is static electricity.

Current, however, can be controlled. Current is what we use to basically do everything unless you are Amish.

Current is controlled by using devices such as resistors, circuits, and switches.

CPO Notes 16.2. And 16.3 Current and Voltage, Resistance and Ohm’s Law

Electric current is measured in amperes or “amps.” In dealing with electricity, amps are the true danger, even small amount of amps running through your body can kill you.

Voltage is the potential energy of electricity. Voltage is power per amp of current that flows. When you multiply volts and amps, you get watts.

A battery converts chemical energy to electrical energy. The chemical reactions between the acids and metals in the battery generate a small, but useful current.

Resistance limits the flow of current. Resistance and current are inversely related. If current is high the resistance is low.

Resistance is measured in ohms. We use the Greek letter omega to represent ohms.

Ohm’s Law states that current is directly related to voltage and inversely to resistance.

I = V

R

Conductors allow electrons to travel through (low resistance), insulators not (high resistance). Semiconductors are in the middle.

CPO 17.1 and 17.2

Magnets have north and south ends. These are called poles. You can not have a north pole with out a south pole.

Magnetic materials usually have a mixture of the metals like iron, nickel and cobalt.

The area in which a magnet attracts is called the magnetic field. The Earth has a magnetic field. The geographic north is actually magnetically south.

The Earth’s magnetic field is created by the rotation metals in the earth’s core.

The unit of magnetic strength is a gauss. The Earth’s magnetic field is .5 gauss, while your refrigerator magnets are around 200 gauss

Electromagnets are created when an electrical current is run through a magnetic material.

Electromagnets are very useful. They are used in all sorts of stuff like toasters, door bells, roller coasters and trains.

Electromagnets are better than permanent magnets because...

1. You can turn them off
2. You can reverse the polarity
3. You can adjust their strength

CPO 17.3 and 17.4

Electric motors convert electrical energy into mechanical energy. These devices have permanent magnets that attached to a rotor. An electromagnet either attracts or repulses the permanent magnet in a repeating pattern. The commutator changes the direction of current which then changes the polarity of the electromagnet.

The rotating part of the motor, including the electromagnetic coils is called the armature.

Generators do the opposite of an electric motor in that they take mechanical energy and convert it into electrical energy. Generators move a magnet around a wire to induce a current. This process is known as electromagnetic induction.

Generators require an external source of energy. This source of energy is traditionally created from the combustion of non-renewable fossil fuels. While this is economically sensible, it is bad for the environment.

The challenge that all societies face is how to create more electricity from renewable sources such as hydroelectric, solar, geothermal and wind.

CPO 12.1 The structure of an atom

Atoms are really small but very important. Everything is made of atoms. But what makes up the atom?

The atom is made of three sub-atomic particles; protons, neutrons, and electrons.

Protons carry a positive charge and they are in the nucleus

Neutrons carry a neutral charge and are also in the nucleus

Electrons carry a negative charge and orbit the nucleus in the electron cloud.

The nucleus is very dense and small. Electron cloud is immense. A dime in middle of Ford field would be the nucleus; the rest of the stadium would be the electron cloud.

Atomic number tells you how many protons are in one atom of the element. It also indirectly tells you the electrons.

Mass number tells you the protons and neutrons. To calculate the number of neutrons in an atom, you subtract the atomic number from the mass number. Fluorine has a mass of 19 and a number of 9. 19-9 = 10 neutrons

Isotopes are when the atoms of the same element have different number of neutrons.

CPO notes 12.2 and 12.3

Electrons are arranged around the atom in energy levels. The amount of electrons in each energy level increases. Just like seats around an arena. If you get farther away from center court (nucleus) there will be more seats (electrons)

1^st level can hold 2 electrons.

2^nd level can hold 8 electrons

3^rd level can hold 8 electrons

4^th level can hold 18 electrons.

To create light, the outer electrons are excited with energy to the point they jump to another level, but they come back.

The periodic table is organized into groups and periods. There are 7 periods and 18 groups. The period tells you the number of electron energy levels.

Most elements are metals. All non-metals, except for hydrogen, are on the right hand side of the table. A few elements, known as the metalloids, have characteristics of metals and non-metals.

Since atoms are so small, scientist use the atomic mass unit (AMU) to measure them.

The main families of elements are the alkali metals, alkaline earth metals, transition metals, boron, carbon, nitrogen, oxygen, halogens, and noble gases.

CPO 12.4

Most elements on the periodic chart are metals and solids

To create an alloy, you need to mix metals. Alloys are better than pure metals. Alloys t end to be stronger and less reactive. The process of making alloys is nothing new. 6, 000 years ago is

known as the Bronze Age. Bronze is an alloy made from tin and copper.

Alloys are made by melting and mixing together metals. Steel is

an extremely important alloy that is used in virtually everything. Cars, buildings, construction equipment, frying pans, etc.

Carbon is the backbone of organic chemistry. Virtually all the molecules that make up plants and animals are constructed around carbon. This is why humans are known as “carbon based life c forms.”

Nitrogen is also very important for life. But we cannot get it by breathing. It has to be bonded to oxygen to create nitrogen dioxide. This is done by bacteria in the soil.