﻿ Introduction to Physics I | Institute of Liberal Arts and Sciences | NU OCW
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# Introduction to Physics I

Yuichi MIURA Associate Professor

Department: Institute of Liberal Arts & Sciences

 Class Time: 2011 Spring Friday Recommended for: Students of the Faculty of Science, without background knowledge of physics

## Course Overview

### Course Contents

Firstly, the following physical concepts will be shown: Velocity and Acceleration, Momentum, Angular momentum, Torque and Momentum inertia.

We will then analyze mechanical phenomena using Energy conservation Law, Momentum conservation Law, and an Equation of Motion.

Physics demonstrations in this lecture:
In order to understand the laws of physics, several demonstrations will be shown. Some interesting questions will also be posed. For example,

• Does mass exist in a gravity-free space station?
• Look for a way to measure the mass of an astronaut in the space station.

The roles of Physical laws in Chemistry and in Bio-Science are also taught in the lecture.

### Key Features

Some of the conclusions from mechanics can be expected, and others are beyond expectations. This is because many premises are taken for granted in our daily lives. In this course students will apply mechanical laws to many real examples in order to acquire actual understanding.

For instance, "friction" is regarded as a "villain" that causes energy losses. However, if there was no friction, what would happen? Floors would be so slippery that you could just not come to university. By examining laws and premises as just described, we will deepen our understanding.

For example, we will apply laws to actual accidents, estimate danger quantitatively, and consider what safety countermeasures should be. Calculations let us conclude, not that "there seems to be something dangerous about it," but that there is as much danger as "that of smashing skulls." Furthermore, this allows us to rationally judge what kinds of improvement are necessary for safety.

In addition we will examine the relationship between phenomena that seem unrelated to each other. One example is the origin of air "pressure." You may not think that "knocking balls" against a wall in tennis and air pressure have the same origin. We can explain pressure by the mechanical laws describing collisions of molecules with walls.

Neither complex biological phenomena nor chemical reactions are allowed to ignore physical laws. Even though it is not superficially obvious, they definitely obey the laws. "Thermodynamics" and "statistical mechanics" are necessary for explaining them, and I will introduce some of their essential concepts. For example, I will introduce the relationship between "disorder" and energy.

In order to understand the laws intuitively, students will carry out some simple experiments at their desks. Some of them are introduced on this website. I would like you to consider and study them.

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## Syllabus

### Course Objectives

This course aims to equip students with an understanding of physical laws, especially "mechanical laws," and the ability to apply these laws to real problems and calculate them. By doing this, students will acquire attitudes to rationally understand natural phenomena.

We live under the assumption of mechanical laws so that the mechanical laws are common sensual. This makes the mechanical laws more difficult to learn rather than easier. For example, the reason why you can catch a ball thrown by another person is that you can anticipate its orbit empirically. However, if there were no gravity or air, the empirical laws could not enable you to cope with thrown balls.

You should pay attention to the definitions of words, because some everyday words are confusingly used as physical technical terms with different meanings. For example, "momentum" is the "quantity of movement" of a moving body. "Work" in physics does not offer wages, but it can generate electricity. Furthermore, even if you have a heavy load on your shoulder, the amount of "work" will be evaluated as zero in spite of your tiredness.

On earth we do not have to distinguish "weight" from "mass," but in a space station you have to. If weight disappears, does mass disappear? How is a "weight check" done in space? These things can be understood by using laws.

Some terrible accidents have happened because simple laws were ignored or made little of. Let's calculate what causes how severe such dangers are. You will find that many accidents have happened because of ignorance of physical laws. Some examples show that phenomena which look very different microscopically to macroscopically follow the same laws. The aim is to equip students with logical attitudes to tackle a variety of natural phenomena by reading their laws.

### Course Requirements

High school-level physics knowledge is not necessary for this course.

### Related Resources

None. Handouts will be distributed when necessary.

### Precautions

I will provide question-and-answer periods, so students may resolve their questions early. Because this is not a course where memorization by heart is required, you will be allowed to use textbooks and notebooks during the exams. Please look forwards to simple experiments that will be carried out in order to deepen your understanding of the course contents.

### Course Schedule

Session Contents
1 Mechanics of a Particle; Velocity, Acceleration
2 Force, inertial Mass
3 Parabolic motion and free Fall
4 Oscillations; Pendulum, Resonance
5 Kinetic Energy and Potential energy
6 Energy conservation law, Friction loss
7 Gravity and the motion of the Planets, Kepler's law
8 Momentum conservation law; Elastic collision of Molecules and Pressure
9 Action and reaction; Jet propulsion
10 An inertial coordinate system and inertial Force
11 The two-body problem; rotation center of a Double star
12 Mass-center and Relative motion
13 Angular momentum and Kinetic energy of rotation
14 Bernoulli's theorem

Weekly reports and a final examination.

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## Class Materials

### Lecture Handouts

Introduction of physical law examples (PDF, 2579KB)

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Page last updated June 5, 2012

The class contents were most recently updated on the date indicated. Please be aware that there may be some changes between the most recent year and the current page.