SI units
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What are the SI base units for mass, length, time, current, and temperature?
The SI base units are: mass (kilogram, kg), length (meter, m), time (second, s), current (ampere, A), and temperature (kelvin, K). These units form the foundation for all other physical measurements.
Express the derived unit for force (Newton, N) in terms of SI base units.
Force (N) is defined as mass × acceleration (F=ma). Therefore, 1 N = 1 kg × m/s² = kg m s⁻².
How can you use SI base units to check the homogeneity of a physical equation?
An equation is homogeneous if the units on both sides are the same. Express all terms in SI base units and simplify; if the units match, the equation is likely correct (but this doesn't guarantee correctness).
What is the meaning of the prefix 'micro' (μ) and what power of 10 does it represent?
The prefix 'micro' (μ) represents 10⁻⁶.
Convert 500 picoseconds (ps) into seconds (s), expressing your answer in scientific notation.
Since pico (p) represents 10⁻¹², 500 ps = 500 × 10⁻¹² s = 5 × 10⁻¹⁰ s.
Express a frequency of 2.5 GHz in Hz. Show your working.
Giga (G) means 10⁹, so 2.5 GHz = 2.5 × 10⁹ Hz = 2,500,000,000 Hz.
The equation for potential energy is PE = mgh. Using SI base units, show that both sides of the equation have the same units.
PE: Energy is measured in Joules (J) and 1J = kg m² s⁻². mgh: kg × m/s² × m = kg m² s⁻². Both sides have the same base units.
What is the purpose of using prefixes like 'kilo' or 'milli' in SI units?
Prefixes are used to express very large or very small quantities in a more manageable and easily understandable form. They provide a convenient way to avoid writing many zeros.
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