Podcast
Questions and Answers
Which one of the following is NOT a fundamental quantity in physics?
Which one of the following is NOT a fundamental quantity in physics?
Derived quantities in physics can be obtained by adding or subtracting fundamental quantities.
Derived quantities in physics can be obtained by adding or subtracting fundamental quantities.
False
What are the three basic units in the CGS system?
What are the three basic units in the CGS system?
Centimeter, gram, second
The unit of electric current is the ______.
The unit of electric current is the ______.
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Match the fundamental quantities with their units:
Match the fundamental quantities with their units:
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Which of the following represents a derived quantity?
Which of the following represents a derived quantity?
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There are ten fundamental quantities in physics.
There are ten fundamental quantities in physics.
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List two examples of supplementary quantities.
List two examples of supplementary quantities.
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What is the least count of a vernier calliper in mm?
What is the least count of a vernier calliper in mm?
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A micrometer screw gauge has a main scale graduated in centimeters.
A micrometer screw gauge has a main scale graduated in centimeters.
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What is the total reading if the main scale reading is 2.3cm and the vernier scale reading is 0.15cm?
What is the total reading if the main scale reading is 2.3cm and the vernier scale reading is 0.15cm?
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The formula for calculating the least count of a micrometer screw gauge is __ divided by the number of divisions on the thimble scale.
The formula for calculating the least count of a micrometer screw gauge is __ divided by the number of divisions on the thimble scale.
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Match the following measurements tools with their accuracy:
Match the following measurements tools with their accuracy:
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What unit of length is used in the FPS system?
What unit of length is used in the FPS system?
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The MKS system uses pound as its unit of mass.
The MKS system uses pound as its unit of mass.
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What is the name of the clocks that are the most accurate in the world?
What is the name of the clocks that are the most accurate in the world?
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In the MKS system, the unit of time is the _.
In the MKS system, the unit of time is the _.
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Match the measurement systems with their units for length:
Match the measurement systems with their units for length:
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Which of the following is an application of dimensional analysis?
Which of the following is an application of dimensional analysis?
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Weight of a body remains constant regardless of the change in gravity.
Weight of a body remains constant regardless of the change in gravity.
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What is the dimensional formula for force?
What is the dimensional formula for force?
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The primary purpose of a ticker tape timer is to measure both _ and _ simultaneously.
The primary purpose of a ticker tape timer is to measure both _ and _ simultaneously.
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Which practical unit is derived from the concept of power?
Which practical unit is derived from the concept of power?
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The smallest division on a meter rule is 0.1mm.
The smallest division on a meter rule is 0.1mm.
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What principle does a spring balance operate on?
What principle does a spring balance operate on?
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The dimension of velocity is expressed as _.
The dimension of velocity is expressed as _.
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What is the relationship between the main scale and the vernier scale in a vernier caliper?
What is the relationship between the main scale and the vernier scale in a vernier caliper?
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The SI system is a modification of the MKS system.
The SI system is a modification of the MKS system.
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Study Notes
Units and Measurements
- Physics: A physical science studying matter, energy, and their interactions.
Branches of Physics
- Introduction to Physics
- Mechanics
- Thermal Physics
- Electricity and Magnetism
- Waves and Optics
- Modern Physics
Quantities and Units
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Physical Quantities: Measurable parameters in physics.
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Fundamental Quantities: Independent quantities (e.g., mass, length, time).
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Derived Quantities: Dependent quantities, calculated from fundamental ones through multiplication or division (e.g., velocity, force). Do not subtract or add to derive these.
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Fundamental Quantities and Units (7 generally accepted, 5 basic):
- Mass (kilogram, kg)
- Length (meter, m)
- Time (second, s)
- Thermodynamic temperature (Kelvin, K)
- Electric current (Ampere, A)
- Luminous intensity (Candela, cd)
- Amount of substance (mole, mol)
- Plane angle (radian, rad)
- Solid angle (steradian, sr)
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Systems of Units:
- CGS (centimeter-gram-second)
- FPS (foot-pound-second)
- MKS (meter-kilogram-second)
- SI (International System of Units): A widely used modification of MKS.
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Practical Units: Fundamental or derived units used in specific contexts. Examples of Practical Units include a light year(distance), or horsepower (power).
Measurement of Time
- Time is measured using stopwatches, clocks, and ticker tape timers.
- Accurate clocks include atomic clocks and quartz crystal clocks.
- Sidereal time is used in astronomy.
- Ticker tape timers measure both distance and time simultaneously.
Measurement of Mass
- Mass is the quantity of matter.
- Measured using beam balances or chemical balances, which use the principle of moments.
- Mass is constant and does not change with gravity.
Measurement of Weight
- Weight is the gravitational pull on an object.
- Measured with spring balances, which operate based on Hooke's Law.
- Weight varies with gravity.
Dimensional Formula
- Dimensional formula expresses a physical quantity in terms of fundamental units (M, L, T.).
- Steps to write a dimensional formula:
- Write the equation for the physical quantity.
- Express all quantities in terms of fundamental quantities.
- Replace fundamental quantities with M, L, T.
- Indicate powers.
Dimensional Analysis
- Used to:
- Verify the dimensional correctness of an equation (principle of homogeneity)
- Convert units between systems (e.g., CGS to SI)
- Develop relationships between quantities
- Determine the dimensions of physical constants from equations
Measurement Instruments
- Meter Rule: Measures length with accuracy to 0.5 mm (0.05 cm).
- Vernier Caliper: Measures length with higher accuracy to 0.1 mm (0.01 cm), typically used for small items like object thickness.
- Micrometer Screw Gauge: Measures very small lengths with accuracy to 0.01 mm (0.001 cm), often used for very thin objects or small diameters.
SI Prefixes
- A table of SI prefixes and their values in powers of 10.
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Description
Explore the essential concepts of units and measurements in physics. This quiz covers various physical quantities, including fundamental and derived quantities, and the systems of units used in physics. Test your knowledge on the basic parameters that define the physical world.
