Physics & Laser BAS 111 Lecture 1: Measurements

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Questions and Answers

What does a scientific measurement require?

  • The tools necessary for the measurement.
  • The definition of the physical quantity and units. (correct)
  • The result of previous measurements.
  • Only a definition of the physical quantity.

In the Système International (SI) of units, what are derived units?

  • Units expressed in terms of one or more base units. (correct)
  • Units that cannot be expressed in terms of base units.
  • Units that require measurement tools to define.
  • Units that are only applicable in specific scientific fields.

Which of the following best describes mass?

  • The gravitational force acting on an object.
  • The total distance an object travels.
  • The time taken for an event to occur.
  • The measure of matter contained in an object. (correct)

Which of the following quantities is considered a basic quantity?

<p>Length (A)</p> Signup and view all the answers

What is the main focus of physics as studied in this course?

<p>The interactions of basic components of the universe. (B)</p> Signup and view all the answers

What is the SI unit for measuring time?

<p>Second (D)</p> Signup and view all the answers

Which component of a pendulum clock is responsible for keeping the pendulum swinging?

<p>Mass at the end of the chain (B)</p> Signup and view all the answers

Which type of stopwatch is known for measuring time with greater accuracy?

<p>Digital stopwatch (B)</p> Signup and view all the answers

What describes the time for one complete oscillation of a pendulum?

<p>Period (A)</p> Signup and view all the answers

What primarily keeps quartz crystals vibrating in most watches?

<p>Electric battery (C)</p> Signup and view all the answers

What are the SI units for density?

<p>kg/m³ (A)</p> Signup and view all the answers

Which of the following equations correctly defines pressure?

<p>Pressure = Force ÷ Area (B)</p> Signup and view all the answers

What is the derived unit for work?

<p>N·m (B)</p> Signup and view all the answers

Which prefix corresponds to a factor of $10^{-6}$?

<p>micro (D)</p> Signup and view all the answers

How is speed defined in terms of its derived units?

<p>m/s (C)</p> Signup and view all the answers

What is the SI unit for force?

<p>Newton (B)</p> Signup and view all the answers

Which of the following is NOT considered a base quantity?

<p>Volume (A)</p> Signup and view all the answers

What does the prefix 'giga-' represent?

<p>10⁹ (A)</p> Signup and view all the answers

Flashcards

What is physics?

Physics is the study of the basic components of the universe and their interactions.

Measurement in Physics

A scientific measurement requires defining the physical quantity and the units used to describe it. The result is a number multiplied by a unit.

SI units

The internationally accepted system of units (metric system) for scientific measurements.

Base quantities

The fundamental quantities used to define other quantities in physics.

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Derived quantities

Quantities expressed using combinations of base quantities.

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Time measurement unit

The second (s) is the SI unit for measuring time.

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Pendulum clock's mechanism

Pendulum clocks use the regular oscillation of a pendulum to measure time, converting gravitational potential energy from a descending weight into a constant swinging motion of the pendulum.

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Quartz watches

Quartz watches use the precise vibration of quartz crystals to keep accurate time.

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Stopwatch types

Stopwatches are categorized into digital and analog types, with digital stopwatches offering higher precision (0.01 seconds) compared to analog stopwatches (0.1 seconds).

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Density definition

Density is the mass of a substance per unit volume.

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Derived Quantity

A physical quantity that can be expressed as a combination of base quantities.

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SI Units

International System of Units; a standard set of units used in science and engineering.

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Area

The extent of a two-dimensional surface, calculated as length multiplied by width.

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Volume

The amount of three-dimensional space occupied by an object, calculated as length multiplied by width multiplied by height.

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Speed

The rate at which an object covers distance (distance/time).

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Acceleration

The rate at which an object's velocity changes over time.

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Pressure

Force per unit area.

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Prefixes

Units used to represent very large or small numbers. By multiplying with a power of 10.

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Study Notes

Course Information

  • Course Title: Physics & Laser
  • Course Code: BAS 111
  • Department: Physics
  • Lecturer: Dr. Yasser Abdou
  • Email: [email protected]

Lecture 1: Measurements

What is Physics?

  • Physics is the study of the basic components of the universe and their interactions.
  • Theories of physics must be verified by experimental measurements.

Measurement

  • A scientific measurement requires the definition of the physical quantity and its units.
  • The value of a physical quantity is a number multiplied by a unit.
  • The precision of a measurement result depends on the procedures used to make the measurement.

Basic Measurements

  • Length: Measuring the distance between two points.
  • Time: Measuring how long an event takes.
  • Mass: Measuring the amount of matter.

The Système International (SI) of Units

  • The SI, or metric system, is the internationally accepted system of units for scientific measurements.
  • The SI consists of base units and derived units.
    • Base units are fundamental units for measuring physical quantities.
    • Derived units are combinations of base units.

Physical Quantities

  • Physical quantities are classified into base quantities and derived quantities.
    • Base quantities are the foundational quantities upon which other quantities are based.
    • Derived quantities are obtained by combining base quantities through relationships.
  • Example: Speed is a derived quantity, calculated from distance and time.

SI Base Units

  • Length: Meter (m)
  • Time: Second (s)
  • Mass: Kilogram (kg)
  • Amount of substance: Mole (mol)
  • Electric current: Ampere (A)
  • Thermodynamic temperature: Kelvin (K)
  • Luminous intensity: Candela (cd)

SI Derived Quantities

  • Area: m²
  • Volume: m³
  • Density: kg/m³
  • Speed or Velocity: m/s
  • Acceleration: m/s²
  • Force: kg⋅m/s² (Newton)
  • Pressure: N/m² (Pascal)
  • Work: N⋅m (Joule)
  • Power: J/s (Watt)

Prefixes

  • Prefixes are used to denote very large or very small quantities.
  • Example: kilo (1000), milli (0.001)

Alternative Writing Method (Standard Form)

  • Expressing very large or very small numbers as N × 10n, where 1 ≤ N < 10 and n is an integer.

Key Concepts

  • A physical quantity is a quantity that can be measured, consisting of both numerical magnitude and unit.
  • Physical quantities are classified into base quantities and derived quantities.
  • There are seven base quantities (length, mass, time, electric current, thermodynamic temperature, amount of substance, luminous intensity).

Questions (from the slides)

  • Questions regarding base quantities, convenient ways of writing quantities, and converting units were presented. These are not the answers but rather questions for the student.

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Lecture 1: Measurements - Physics & Laser (BAS 111) PDF

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