Physics: Measurements and Units

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Questions and Answers

Which of the following is NOT a base quantity in the SI system?

  • Mass
  • Time
  • Energy (correct)
  • Length

The unit for electric current is millivolt.

False (B)

What prefix is used in the SI system to denote one thousandth (1/1000)?

milli

One mole contains _____ particles, known as Avogadro's constant.

<p>6.02 x 10²³</p> Signup and view all the answers

Match the following base quantities with their SI units:

<p>Length = Metre Mass = Kilogram Time = Second Temperature = Kelvin</p> Signup and view all the answers

Which of the following is a derived quantity?

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

Waves transfer both energy and matter.

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

What is the unit symbol for the SI unit of thermodynamic temperature?

<p>K</p> Signup and view all the answers

What is the prefix that corresponds to the factor of $10^6$?

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

A digital micrometer screw gauge can measure lengths up to 10 centimeters.

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

What is the SI unit for length?

<p>metre</p> Signup and view all the answers

The smallest unit an instrument can measure is known as its __________.

<p>precision</p> Signup and view all the answers

Match the following measuring instruments with their range:

<p>Measuring tape = zero to several metres Metre rule = zero to one metre Digital calipers = zero to 15 centimetres Digital micrometer screw gauge = zero to 2.5 centimetres</p> Signup and view all the answers

Which of the following is an example of a scalar quantity?

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

Parallax errors are a type of measurement error that occurs when the measurement is not taken straight on.

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

What device is considered the most accurate timekeeping device?

<p>Atomic clock</p> Signup and view all the answers

Which of the following is a vector quantity?

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

Speed is a scalar quantity.

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

What is the SI unit of mass?

<p>kilogram</p> Signup and view all the answers

The prefix 'kilo-' denotes a factor of ______.

<p>1000</p> Signup and view all the answers

Match the instrument to its appropriate use:

<p>Metre rule = Measuring longer distances Micrometer screw gauge = Measuring small thicknesses Measuring tape = Flexible measuring for curved surfaces Digital calipers = Precise measurements of depth</p> Signup and view all the answers

What is the approximate result of a car moving 90 km/h due east for one hour and then 60 km/h due west for one hour?

<p>30 km/h due west (C)</p> Signup and view all the answers

Accurate measurement tools such as digital calipers can provide readings with greater precision than a metre rule.

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

What is Avogadro's constant?

<p>6.022 x 10^23</p> Signup and view all the answers

Flashcards

Physics

The study of the natural world, from the very small to the very large.

Physical Quantities

Quantities that can be measured, including a numerical value and a unit.

SI Units

A system of standardized units for measurements, like the meter, kilogram, and second.

Base Quantities

Fundamental physical quantities like length, mass, and time that are used to define other quantities.

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SI Unit for Length

Metre (m)

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SI Unit for Mass

Kilogram (kg)

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SI Unit for Time

Second (s)

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Derived Quantities

Physical quantities that are defined using equations from base quantities. For example, speed = distance/time.

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Scalar Quantity

A quantity that has only magnitude (size), but no direction.

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Vector Quantity

A quantity that has both magnitude and direction.

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Distance

The total length covered by an object, regardless of direction.

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Displacement

The shortest distance between the starting and ending points, considering direction.

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Speed

The distance covered per unit time.

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Velocity

The rate of change of displacement.

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Graphical Method (Vectors)

A method to add vectors using arrows where length represents magnitude and direction represents direction.

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Prefixes

Symbols and words added to the beginning of a unit to indicate a multiple or sub-multiple of that unit.

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Tera (T)

A prefix representing a multiple of 10¹² (one trillion).

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Micro (µ)

A prefix representing a sub-multiple of 10⁻⁶ (one millionth).

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What is the smallest unit an instrument can measure?

The smallest unit an instrument can measure is called its precision.

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Parallax Error

An error in measurement caused by observing a measurement from an angle, rather than directly perpendicular.

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Zero Error

An error in measurement that occurs when an instrument doesn't start at zero.

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What is a vector quantity?

A quantity that has both magnitude and direction. Examples include velocity, force, and displacement.

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What is a scalar quantity?

A quantity that has only magnitude. Examples include speed, mass, and temperature.

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Study Notes

Physical Quantities, Units, and Measurements

  • Measurements are crucial in daily life, especially during pandemics.
  • Body temperature measurement helps prevent disease spread.
  • A physical quantity consists of a numerical magnitude and a unit.
  • Examples of base quantities (SI units) include mass (kg), length (m), and time (s).
  • Other base quantities are electric current (A), thermodynamic temperature (K), amount of substance (mol).
  • Prefixes (e.g., nano, micro, milli, centi, kilo, mega, giga, tera) are used for submultiples and multiples of SI units.

What is Physics?

  • Physics studies the natural world, from the very large (e.g., solar system) to the very small (e.g., atom).
  • Two key concepts are matter and energy.
  • Disciplinary ideas in physics explain real-life phenomena: Matter and energy make up the Universe; Matter interacts through forces and fields; Forces help us understand motion; Waves transfer energy without transferring matter; Conservation laws constrain changes in systems; Microscopic models explain macroscopic phenomena

What are Physical Quantities?

  • Physical quantities are measurable quantities with magnitude and units.
  • Seven basic physical quantities are used for measurements.
  • The International System of Units (SI) ensures standardized measurements.
  • Standard form and prefixes are useful for representing extremely large or small values.

How do we Measure Physical Quantities?

  • Appropriate instruments are essential foraccurate measurements.
  • Examples include metre rules, measuring tapes, digital calipers, and digital micrometer screw gauges.
  • Precision of an instrument refers to its smallest measurable unit.

What are Scalars and Vectors?

  • Scalar quantities have only magnitude (e.g., distance, speed, mass).
  • Vector quantities have both magnitude and direction (e.g., displacement, velocity, force).
  • Vectors can be added graphically (head-to-tail method).
  • Distance and displacement are related but distinct concepts.
  • Speed and velocity are related but distinct concepts.

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