Physical Science Projects

Physical science is the science of chemistry, physics and astronomy. To discuss just two elementary concepts of physics, I’m going to ask you to keep a little red race car in mind. Then we’ll talk about the solar system. All we’ll do today is define terms, and ask some questions.

Physics is the science that deals with matter, energy, motion, and force.

Can you tell me what is the energy and matter in a revved up racecar? That was an easy one. Can you define what speed is, in relation to the race car?

Speed is the motion of course. Speed tells us how fast the car is going, right? Speed is the distance per time. It is one dimensional.

That’s fine. But there are two kinds of speed. One is the thing you’re doing at any one second, as in 45 mph. when flagged by the police. Right. That’s called instantaneous speed. The second speed is the average speed in a given period of time, as in the speed you averaged, say 40 mph, on the one hour trip home from school. Why are the differences important? Just get the definitions straight, eventually you’ll see.

The next term is velocity. Velocity is two dimensional. It is the distance per time but it also includes direction. The formula for velocity is v=at when v means velocity, a means acceleration, and t means time. So you would say that the race car was going 95 mph and 5 degrees north north east. Velocity is the speed at which an action accelerations in the direction it is moving.

Here’s a thought: If something is moving at a constant speed, is it moving at a constant velocity? Reworded, we have a hypothesis. An object moving at a constant speed is also moving at a constant velocity.

Do you need more information?

Let’s answer with an experiment: Let’s say that the speed of the race car is 0 mph, and the velocity, being both speed and direction, is 0 mph going due West. Could the race car’s velocity in this case be constant? (0 mph, due W). Think about it. This baby isn’t moving at all, and so has no velocity.

What if a car were moving at 35 mph with an average velocity of 35 mph for 30 minutes, heading about 45 degrees west? Velocity changes as the direction changes.

To get back to our hypothesis: that something moving at a constant speed would also be moving at a constant velocity. Since there is an exception, even if only one, the whole hypothesis is wrong. This is very elementary physics. But it is a beginning.

Let’s move on to Astronomy. O.K., rocket science. Astronomy is the science that deals with the universe beyond the earth's atmosphere. It does have to do with rockets, but it also concerns galaxies, black holes, quarks, and any number of other glorious objects, most of which, by the way, cannot be seen without a telescope. Can you name a famous telescope?

What you can see in the night sky is the difference between a planet and a star. Do you know how to tell the difference? …”Twinkle, twinkle, little star, how I wonder what you are…” Stars twinkle and planets don’t. That’s right, the light from a star twinkles whereas the light from a planet doesn’t. Do you have any ideas about why that is?

Do you have the idea that maybe the light from a star is actually a lot of energy which we perceive as light, whereas the light from a planet is just reflected light, which doesn’t possess any energy of its own.

Why do you think energy would twinkle? Does a fire sort of twinkle? Yes, a star is really a gigantic fire burning in the empty sky. Now, why it doesn’t fall apart or fall down onto the earth is a lesson for another day.

P.S. Where does the light come from that the planets reflect?