Physics 100

Dr. Edward Rhoads

LD 156P

317-278-1134

erhoads@iupui.edu

Goal: To understand what Science is, what it does, and as to how Physics is useful to our society.

Objectives:

1. To understand Scientific Models

2. To learn about Scientific Theory

3. To Brainstorm uses for Physics

What is Science?In order to understand what science is you will first need to see how it

works.

To attempt to gain an understanding of how science works we will work on the following example:

You are buying a house. The house is $100,000.The loan is 6% interest for 30 years.You go to a website to figure out what your monthly payment will be

and it tells you $600.

How much money will you end up spending on this house in the 30 years of the mortgage?

NOTE: we are attempting to create a model here – a mathematical model.

What is Science?

You are buying a house. The house is $100,000.The loan is 6% interest for 30 years.

$600/ month * 12 months/year * 30 years =$216,000

Is this the “correct” answer?

Assumptions

• Assumptions are values we assume to be true or that their effect on the final result is negligible.

• What have we assumed here?

Assumptions

• Constant interest rates

• Constant payment each month

• Constant dollar

• Monthly interest, and payment made after interested compounded (if payment is made before interest, then needed payment drops to $597 per month).

Omissions

• Insurance• Escrow• Lenders fees• Taxes and insurance• There are always other unknowns.

• So, is $216,000 “wrong” answer?• A) yes• B) no

• How could we include these without knowing what they will be?

Error Bars

• Error Bars are just the value we expect the true value to deviate from our model.

• The smaller the error bar the more accurate our model is.

In Science:

Unless you have made a math error or physics error in your model there is no “right” or “wrong” answer. There are only answers that are highly accurate, moderately accurate, and not very accurate. Okay, occasionally there is a “crackpot” idea also, but those are rare and usually ignored by most – however….

Science:

Is the ongoing work to attempt to understand what we do not know using what we do know. We do this by attempting to best address the “error bars” both known and unknown that we may encounter in order to establish the most accurate set of ideas (otherwise known as “models” or “theories”) that we possibly can.

What is a “theory”

a) Some random guess.b) What some scientist thinks the answer should

be off the top of his head.c) Some unproven and/or un-provable idea which

is the most educated guess someone can make.

d) The “model” which most accurately explains what we can observe and find in experiments, and has been proven to be accurate time after time after time.

What is Physics used for?

With a neighbor, brainstorm as many things that you can think of that Physics has been, or could be, used for. Include even historical reasons, and possibly future ones.

Conclusion

• Science is about using as many facts as possible to take the next step in understanding the unknown.

• Many “theories” are in fact well thought out and very well proven using as many tests, observations, and experiments we can think of.

• Physics is a very useful science and will only become more useful as mankind heads into the future.