Basic Physics Reviewer, Study notes of Physics

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LECTURE NOTES ON BASIC PHYSICS

COMPILED BY: CHIBUIKEM N. OKEKE

TABLE OF CONTENTS

• CHAPTER ONE
• 1.0. Introduction to Physics
• 1.1. Branches of Physics
• 1.2. Scientific Methods
• CHAPTER TWO
• 2.0. MEASUREMENTS
• 2.1. Fundamental quantities and fundamental units
• 2.2. Derived quantities and derived units
• 2.3. Scalar quantities
• 2.4. Vector quantities
• CHAPTER THREE
• 3.0. MOTION
• 3.1. Position, Distance and Displacement
• 3.2. Speed and Velocity
• 3.3. Acceleration
• 3.4. Force (F)
• 3.5. Friction
• 3.6. Work (W)
• 3.7. Energy
• 3.8. Newton's Laws of Motion
• 3.9. Power (P)
• CHAPTER FOUR
• 4.0. Wave and Types
• 4.1. Classification of Waves
• 4.2. Wave Terms
• 4.3. Properties of waves

forces but also the nature and origin of gravitational, electromagnetic, and nuclear force fields.

1.1. Branches of Physics

Physics is generally divided into: Classical and Modern physics

Classical physics are the fundamental areas of physics upon which other phenomena in physics were built. They are the background areas of physics. Examples of such areas of physics are: Mechanics, Principles of Electromagnetism, Thermodynamics, Electricity, Magnetism, etc.

Modern physics began in the early 20th century with the work of Max Planck in quantum theory and Albert Einstein's theory of relativity. It is a development from the classical branch of Physics. Modern physics covers such areas as: Astrophysics, Nuclear physics, Geophysics, Neurophysics, etc.

1.2. Scientific Methods

Four an accurate understanding of physics, the following steps or methods are necessary: a. Concept: This talks about a general notion or idea about a topic or subject; an idea of something formed by mentally combining all its characteristics or particulars; a construct. The first step/method for an accurate understanding of physics is a full grasp of the concepts of the particular topic in question.

b. Theory and Experiment: Theorists seek to develop mathematical models that both agree with existing experiments and successfully predict future experimental results, while experimentalists devise and perform experiments to test theoretical predictions and explore new phenomena. Although theory and experiment are developed separately, they strongly affect and depend upon each other. Progress in physics frequently comes about when experimental results defy explanation by existing theories, prompting intense focus on applicable modeling, and when new theories generate experimentally testable predictions, which inspire the development of new experiments. This is the second step in scientific methods.

c. Application: Application of the principles of physics brings in an area of physics known as Applied physics. It is a general term for physics research, which is intended for a particular use. An applied physics curriculum usually contains a few classes in an applied discipline, like geology or electrical engineering. It usually differs from engineering in that an applied physicist may not be designing something in particular, but rather is using physics or conducting physics research with the aim of developing new technologies or solving a problem. This is the last step in scientific methods

Density Mass/volume Kgm-^3

Velocity Displacement/time Ms-^1

Acceleration change in velocity/time Ms-^2

Weight Mass x acceleration due gravity Newton (N)

Momentum Mass x velocity

Newton second (Ns)

Pressure Force/ area Pascal or Nm-^2

Energy/work Force X distance Joule (j) or Ns

Power Work/time Watt(w)/js- (^1) /NmS- 1

Physical quantities are further divided into two when considering magnitude and direction. They are: Scalar and vector quantities. A quantity that has magnitude but no particular direction is described as scalar. A quantity that has magnitude and acts in a particular direction is described as vector.

2.3. Scalar quantities

Scalar quantities only have magnitude (size). For example, 11 m and 15 ms-1^ are both scalar quantities. Scalar quantities include: distance, speed, time, power, energy Scalar quantities change when their magnitude changes.

2.4. Vector quantities

Vector quantities have both magnitude and direction. For example, 11 m east and 15 ms-1^ at 30° to the horizontal are both vector quantities. Vector qualities include: displacement, velocity, acceleration, force, weight, momentum. Vector quantities change when:

 Their magnitude changes  Their direction changes  Their magnitude and direction both change The difference between scalar and vector quantities is an important one

CHAPTER THREE

3.0. MOTION

Motion is simply a change of position of a body with time. Motion is caused by Force. There are four basic types of motion: Random, Translational, Rotational and Oscillatory motion.

3.1. Position, Distance and Displacement

The position of an object is the point where the object is in space. Distance is the aspect to which an object has moved from one point to another. Displacement is the distance travelled in a specified direction. It is usually a straight line drawn from the starting point to the end point..

3.2. Speed and Velocity Speed is the rate at which a body covers a distance while Displacement is the rate of change of displacement. They both have one unit; Meters per Second.

3.3. Acceleration This is the rate of change of velocity with time. The S.I. unit of acceleration is Meters per square second Acceleration (a) = (v - u)/t Where v = final velocity, u = initial velocity When velocity increases with time, it is known as Acceleration while when it decreases with time, it is known as Deceleration. Example A car moves from a velocity of 20ms-1^ to a velocity of 30ms-1^ in 5 seconds. What is the average acceleration? Ans = 2ms-

The three notable equations of motion with uniform acceleration are as follows: a. V = u + at b. S = ut + 1/2 at^2 c. V^2 = u^2 + 2as

3.7. Energy Energy is the capacity to do work. Unit is Joule. There are many forms of energy such as mechanical, heat, light, atomic energy, etc. Under mechanics, we focus on Mechanical energy. Mechanical energy is classified into two - Potential and Kinetic energy

Potential energy is a stored energy or energy possessed by a body by virtue of its position and state. It depends on mass, height and acceleration due to gravity. P.E. = mgh

Kinetic energy is the energy possessed by a body by virtue of its motion. Kinetic energy depends on mass and velocity. K.E. = 1/2mv^2

Examples

1. Find the potential energy of a boy of mass 10kg standing on a building floor 10m above the ground level. Ans = 1000J
2. An object of mass 5kg is moving at a constant velocity of 15m/s. Calculate its kinetic energy. Ans = 562.5J

3.8. Newton's Laws of Motion Sir Isaac Newton discovered how forces are related to motion and formulated three important laws: A. First law of Motion Every object continues in a state of rest or uniform motion unless acted upon by an external force. B. Second Law of Motion The rate of change of momentum is proportional to the impressed force and takes place in the direction of that force. C. Third law of Motion Action and reaction are equal and opposite.

3.9. Power (P) Power is the time rate of doing work. The unit of Power is Watts. Power = work/time

CHAPTER FOUR

4.0. Wave and Types

A wave is a disturbance which travels through a medium transferring energy from one point of the medium to another without causing any permanent displacement of the medium.

4.1. Classification of Waves Waves are classified based on: Medium of propagation Direction of travel

Medium of propagation Mechanical waves eg. Sound and water waves require a medium through which to travel, while electromagnetic waves eg. light, radio and x-rays do not require a medium and can be propagated through a vacuum.

Direction of travel Transverse waves eg. Water, light and radio waves are waves which travel perpendicularly to the direction of the vibrations producing the waves while Longitudinal waves eg. Sound waves travel in a direction parallel to the vibrations of the medium.

4.2. Wave Terms

The high point of a transverse wave is a called the crest, and the low point is called the trough. For longitudinal waves, the compressions and rarefactions are analogous to the crests and troughs of transverse waves. The distance between successive crests or troughs is called the wavelength. The height of a wave is the amplitude. How many crests or troughs pass a specific point during a unit of time is called the frequency. The velocity or speed of a wave can be expressed as the wavelength multiplied by the frequency