Physics!
what is Physics?
the main goal in physics is to understand how out universe works.
Physics is the natural science that studies matter, its motion and behavior through space and time, and the related entities of energy and force.
physics is the foundation for all other sciences and is the purest form of knowledge, alongside math.
energy!
energy is the ability to do work.
there is energy in everything.
there are different types of energy like electrical, kinetic, heat, sound and light.
kinetic energy is the energy of motion. Moving things around is a kind of work. The faster an object is moving, the more kinetic energy it has and the more work it can do
potential energy, is energy that is stored in something.
Gravitational energy is the energy stored in an object due to its height above the ground. The higher the object is, the more gravitational energy is stored in it.
Elastic energy is energy stored in a compressed or stretched object, such as a spring or rubber band.
Chemical energy is energy stored in the chemical bonds of a substance. This type of potential energy is found in food, batteries, wood, petrol, and the cells of all living things.
humans and animals need energy to move, eat, work and do everything else.
energy transformation is when one type of energy is converted into another. for example, the elastic energy of a stretched rubber band, is transformed into kinetic energy when released.
energy transfer is when energy is moved from one object to another. for example, when a soccer player kicks a ball, kinetic energy is transferred from his moving leg to the ball.
In most energy transfers and transformations, a small amount of energy is lost to the surrounding air as heat and sound energy
energy transformations and transfers can be clearly represented by a sankey diagram
sankey diagrams show the flow of energy,as a large arrow pointing from left to right. If some of the energy is transformed into other types then the main arrow splits into a number of different arrows
The thickness of each arrow indicates the amount of energy of that type.
The amount of "input" energy is equal to the total "output" energy, therefore the combined thickness of the "output" arrows must be equal to the combined thickness of the "input" arrows.
Energy efficiency is a measure of how much of the total energy supplied is useful energy. Energy that is supplied but not put to the intended use is called waste energy.
To calculate energy efficiency you divide the useful energy by the total input of energy, and multiply this by 100.
The useful energy is shown by the arrows that point to the right and the waste energy is shown by the arrows that curve downward.
Energy is measured in joules (J).
One joule is roughly the amount of kinetic energy needed to lift a small apple to a height of one metre
Although energy can be transferred and transformed in all sorts of ways, it can never be created or destroyed
pendulums!
a pendulum is a weight hung from a fixed point.
common examples of pendulums are clocks, swings, wrecking balls and metronomes.
the length of time a pendulum takes to go oscillate once (go back and forth) is its called the period.
A pendulum will always include: the mass of the bob (the part on the end), the length of the string or rod and the amplitude at which it is released
The mass of the bob and the amplitude do not affect the period. The length however, does. The longer the string or rod the bob is suspended from, the longer the period of the pendulum.
We can predict the length of the period by using the following formula: 2pi x the square root of the length divided by gravity. Gravity is approximately equal to 9.8 m/sec/sec. T represents the period.
For example the period of a pendulum with the string at a length of 1 metre, would be close to 2pi x the square root of 1/9.8. If you calculate this you would get 2 seconds (rounded to 1 sig. fig.)
The higher you are, the greater the maximum velocity and maximum potential energy. This means that the shorter the length, the more potential energy, making the pendulum accelerate faster. The longer the string, the lower the bob is, making the period slower.
The mass does not affect the period. This is because, if mass increases, so does the force on the pendulum, but acceleration remains the same, leading to the same time over which the acceleration occurs.
NOTES/IMPROVEMENTS:
- There isn't much to improve on, but maybe shorter notes
- Maybe a small explanation on heat, light and sound energy
- Maybe what you would learn in physics too?
how does the universe work?