 # Kinetics

Kinetics

Now that we have looked at matter, it is time to look at its movement and a term called energy. The study of movement is called kinetics and is our next unit. This corresponds to pages 51-91 and 95-112 in the textbook. You will learn the basic laws governing motions (Newton’s Laws of motion and gravity) as well as some important formulae. Then you will learn about work and simple machines. All of this newfound knowledge will be applied to various projects. We will also focus on note-taking.

What is energy?

What are the two types of energy?

Potential Energy:

Kinetic energy:

Energy cannot be created or destroyed (except through E=MC2, but that is for another time).

Friction is present in all motions.

Sir Isaac Newton was a great scientist. Along with co-founding a new branch of math called Calculus, he is considered the father of optics (studying light), he put together a theory of gravity that applies to everything, and he founded kinetics (what we are about to study).

Newton’s Law of gravity simply states that every object exerts a gravitational pull on everything else proportional to its mass and inversely proportional to the distance between the objects (squared). Put this in words you will understand and put this in your notebook:

On Earth, objects fall toward Earth at roughly 9.8 m/s2 meaning they accelerate downward about 30 feet per second per second!

Terminal velocity - the speed at which something stops accelerating due to gravity

Center of gravity - the lower, the more stable

Newton then went on to describe three underlying laws of motion. All three should be in your notebook:

1. Law of inertia =

2. Law of force =

3. Law of reaction =

Other kinetic formulae that are important are (these I do not expect you to memorize):

Speed = distance / time

Velocity = speed in a direction

Acceleration = velocity / time

Momentum = mass X velocity

Now we will apply some of these laws to protect an egg from a fall: Egg drops!

Another vital formula dealing with kinetics is work. Make sure this is in your notebook too.

Work =

Simple machines alter the force you get out by altering the distance you put in.

Work in = work out

force X distance in = force X distance out

The six simple machines are (these, too, go in your notebook):

Power is another useful term and should be in your notebook

Power =

We will calculate our own power.

Let's revisit pressure from the matter unit. Using what we now know about force,

Pressure =

Note that pressure is what breaks surfaces. Think of the wedge as a simple machine. It works by putting all the force on a smaller area, therefore increasing pressure.

Check your notebook. Does it have a title something like "Kinetics" followed by everything I said above that you need to have. If so, you should be able to answer these questions from your notebook:

What is energy?

Contrast the two types of energy.

Which factors affect gravity’s pull on you?

Describe each of Newton’s laws of motion.

Be able to apply the correct formula and substitute correctly.

Using what you learned, explain why you expected you egg drop design to survive.

Know the formulae for work and power.

List the simple machines and give a common example of each.

Calculate how much force you will get out of a machine if you know how much went in.

Explain how to use simple machines to magnify your strength and overcome a challenge.

Calculate pressure.

If you have enjoyed the topics in this unit, feel free to investigate further. Here are some ideas. These are NOT required, but I hope you have fun and delve into some of them:

Continue building! Build a super egg drop design that is exceptionally creative or invincible. Build another ball launcher. Build a better jack for lifting my van. Build a simple machine to launch me! Build, build, build!

Sir Isaac Newton was a fascinating man who contributed greatly to science. Research his life. Why was he accused of practicing alchemy? Why did he hold onto his tome on optics for many years before publishing it? Find out.

Make an inventory of all the simple machines in you kitchen (warning, this one make be a bigger project than you think).

Who is the most forceful or powerful member of your family. Design an experiment (it doesn’t need to resemble the ones we did in class), collect you data, and share. Can you design a test that favors you (i.e. which are your most powerful muscles)?

Archimedes stated that he could lift the Earth with a long and strong enough lever. Calculate how long the lever would have to be (how far you would have to move your end) for you to move the Earth.

How does the potential / kinetic energy of a roller coaster work