Foundation Physics - Measurement of Physical Quantities
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Questions and Answers

What constitutes a measurement in physics?

A measurement in physics consists of a number and a unit that quantifies a physical property.

Explain the difference between direct and indirect measurement.

Direct measurement is obtained straight from an instrument's scale, while indirect measurement involves calculating a value using known relationships between quantities.

What is a physical quantity?

A physical quantity is a property of an object that can be expressed in terms of size, magnitude, or amount.

List three types of physical quantities.

<p>Three types of physical quantities are length, mass, and time.</p> Signup and view all the answers

Why is it important to use standard units in measurements?

<p>Standard units ensure consistency and clarity in communication of measurement results among scientists.</p> Signup and view all the answers

What is the SI unit for mass?

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

What derived unit is obtained by dividing length by time?

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

What is the base quantity with the SI unit of Kelvin?

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

Explain what standard form represents in mathematical terms.

<p>Standard form represents a number as a product of a coefficient (1-10) and a power of ten.</p> Signup and view all the answers

What is the derived unit for force based on Newton's Second Law of motion?

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

In standard form, how would the number 7000000 be expressed?

<p>7 x 10^6</p> Signup and view all the answers

What is the SI unit for luminous intensity?

<p>Candela (cd)</p> Signup and view all the answers

What rule should be applied when multiplying two numbers in standard form?

<p>Multiply the coefficients and add the exponents.</p> Signup and view all the answers

What is absolute uncertainty and how is it represented?

<p>Absolute uncertainty is the range of values around a reported measurement, represented as 'value +/- uncertainty'.</p> Signup and view all the answers

How do you calculate relative uncertainty?

<p>Relative uncertainty is calculated by dividing the absolute uncertainty by the reported value.</p> Signup and view all the answers

What happens to absolute uncertainties when adding or subtracting measurements?

<p>The absolute uncertainties are always added when performing addition or subtraction.</p> Signup and view all the answers

Describe how relative or percentage uncertainties are handled during multiplication or division.

<p>During multiplication or division, the relative or percentage uncertainties are summed.</p> Signup and view all the answers

When dealing with measurements raised to an exponent, how do you find the uncertainty?

<p>Multiply the percentage or relative uncertainty by the exponent of the measurement.</p> Signup and view all the answers

What is dimensional analysis and its primary purpose?

<p>Dimensional analysis is a method to check the homogeneity of equations using dimensions for base quantities.</p> Signup and view all the answers

What are the dimensions for density, and how is it derived?

<p>The dimensions for density are represented as $[M][L]^{-3}$, derived from mass divided by volume.</p> Signup and view all the answers

List the symbols used for the base quantities of length, mass, and time.

<p>The symbols are [L] for length, [M] for mass, and [T] for time.</p> Signup and view all the answers

Flashcards

Measurement

The combination of a number and a unit used to quantify a property of an object.

Direct Measurement

A measurement obtained directly from an instrument's scale, such as reading the length of a ruler.

Indirect Measurement

A measurement calculated using a known relationship or formula, where the values of other quantities are measured directly.

Physical Quantity

A property of an object that can be measured and quantified, such as length, mass, time, temperature.

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Scientific Measurement System

A set of logical rules that govern how scientists communicate quantitative information to each other.

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Base Quantity

A fundamental quantity that cannot be expressed in terms of other quantities.

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SI Base Unit

A unit of measurement defined for a base quantity, forming the foundation of the SI system.

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Derived Quantity

A quantity derived from a combination of base quantities, often expressed as a combination of their units.

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Standard Form

A representation of a number as a product of a number between 1 and 10 (the coefficient) and a power of 10 (the exponent).

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Exponent in Standard Form

The power of ten in a number written in standard form, indicating the number of decimal places the decimal point needs to be shifted.

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Coefficient in Standard Form

The number between 1 and 10 in a number written in standard form.

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Converting from Standard Form

Moving the decimal point to the left or right, multiplying or dividing by 10 for each place the decimal is moved, effectively changing the exponent in scientific notation.

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Converting to Standard Form

Expressing a number as a product of a number between 1 and 10 (a coefficient) and a power of 10 (the exponent), effectively shifting the decimal point to the right or left and adjusting the exponent.

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Absolute Uncertainty

The range of possible true values for a measurement, expressed as the reported value plus or minus the absolute uncertainty.

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Relative Uncertainty

The ratio of the absolute uncertainty to the reported value.

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Percentage Uncertainty

The relative uncertainty expressed as a percentage.

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Adding or Subtracting Uncertainties

When adding or subtracting measurements, add the absolute uncertainties.

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Multiplying or Dividing Uncertainties

When multiplying or dividing measurements, add the relative or percentage uncertainties.

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Dimensions

The type of base quantities that make up a physical quantity.

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Dimensional Analysis

A technique to check if a relationship between physical quantities is dimensionally correct.

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Dimensions of Density

Density can be expressed in terms of mass per unit volume, which has the dimensions [M]/[L]^3.

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Study Notes

Foundation Physics - Measurement of Physical Quantities

  • Measurement Defined: Scientists use logical rules to communicate information, requiring results to be expressed as multiples of a standard unit. This ensures consistent communication.

  • Measurement as a Combination: A measurement combines a number and a unit. The number quantifies a property of an object. (e.g., 300 meters)

Types of Measurements

  • Direct Measurement: Direct measurement obtains the value of a physical quantity directly from an instrument's scale. An example of a direct measurement instrument is a vernier caliper. Examples include measuring length with a ruler, mass with a balance, or time with a stopwatch.

  • Indirect Measurement: Indirect measurement calculates the value of a quantity using a known relationship (formula) between that quantity and measurable quantities, obtained through direct measurement. An example is calculating circumference (C) from diameter (d) using the formula C = πd. Another example includes calculating area from measurements of length and width using a known formula (area = length x width) .

Physical Quantities

  • Definition: A physical quantity represents a property of an object, described in terms of size, magnitude, or amount.

  • Examples:

    • Length
    • Mass
    • Time
    • Temperature
    • Amount of Substance
    • Luminous Intensity
    • Current

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Related Documents

PHY 1200 Foundation Physics PDF
PHY 1200 Foundation Physics Standards and Units Lecture Notes PDF
PHY 1200 Foundation Physics Errors/Uncertainties and Dimensional Analysis PDF

Description

Explore the essential concepts of measurement in physics, including definitions, types of measurements, and examples of physical quantities. This quiz will help you understand how scientific communication relies on standard units and the distinction between direct and indirect measurement methods.

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