Derivations of SI Units in my High-School Physics formulas.

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SUMMARY

This discussion focuses on the derivations of SI units for various physics formulas relevant to high school physics in New South Wales, Australia. Key formulas include frequency (f = 1/t) resulting in Hertz (Hz), work (W = Fs) yielding Joules (J), and Ohm's Law (R = V/I) leading to Ohms (Ω). The discussion emphasizes that these derivations do not involve calculus and are limited to one or two-dimensional motion, making them accessible for introductory physics students.

PREREQUISITES
  • Understanding of basic physics concepts such as force, energy, and voltage.
  • Familiarity with SI units including Joules (J), Newtons (N), and Amperes (A).
  • Knowledge of fundamental equations in physics, particularly those related to motion and electricity.
  • Basic comprehension of dimensional analysis and unit conversion.
NEXT STEPS
  • Research the derivation of additional SI units in advanced physics contexts.
  • Explore the applications of Ohm's Law in electrical engineering.
  • Study the relationship between energy and power in different physical systems.
  • Learn about the significance of dimensional analysis in experimental physics.
USEFUL FOR

High school physics students, educators teaching introductory physics, and anyone interested in understanding the foundational concepts of SI units and their derivations in physics.

f3nr15
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I was bored so I make fun with derivations of SI units of many Physics formulas.
Note, this should just be called "introductory physics", that means NO calculus (but rate of change designated by the delta symbol) and motion is in one or two directions only.
This is high school physics level in Australia only (State NSW to be more precise).

Here goes, I hope I'm right.


f = 1/t

Unit: Hz (Hertz)
Derived Unit(s): s-1 (per second)



W = Fs

Unit: J (Joule)
Derived Unit(s): N m (Newton-metre)
Further Derived Unit(s): kg m s-2 x m = kg m2 s-2 (kilogram-metre squared per second squared)

(N = kg m s-2)



q = I/t (I = q/t)

Unit: C (Coulomb)
Derived Unit(s): A s (Ampere-second)

(A = C s-1)



R = V/I [V = IR (Ohm's Law)]

Unit: Ω (Ohm)
Derived Unit(s): V A-1 (Volts per ampere)
Further Derived Unit(s): kg m2 s-3 A-1 x A-1 = kg m2 A-2 s-3 (kilogram-metre squared per Ampere squared-second cubed)

(V = kg m2 s-3 A-1)



V = E/q (V = ΔPE/q)

Unit: V [Voltage (Potential Difference or Electromotive force (emf))]
Derived Unit(s): J C-1
Further Derived Unit(s): kg m2 s-2 x A-1 s-1 = kg m2 A-1 s-3 (kilogram-metre squared per Ampere-second cubed)

(J = kg m2 s-2 & C = A s)



P = E/t

Unit: W (Watt)
Derived Unit(s): J s-1 (Joules per second)
Further Derived Unit(s): kg m2 s-2 x s-1 = kg m2 s-3

(J = kg m2 s-2)



F = ma (Newton's Second Law)

Unit: N (Newton)
Derived Unit(s): kg m s-2 (kilogram-metre per second squared)

(a = m s-2 = N kg-1)



B = F / LI (F = LIB)

Unit: T (Testla)
Derived Unit(s): N m-1 A-1 (Newton per metre-Ampere)
Further Derived Unit(s): kg m s-2 x m-1 x A-1 = kg A-1 s-2 (kilogram per Ampere-second squared)

(N = kg m s-2)

&

Wb m-2 (Weber per metre squared)



Ф = BA

Unit: Wb (Weber)
Derived Unit(s): T m2 (Testla-metre squared)
Further Derived Unit(s): kg A-1 s-2 x m-2 = kg A-1 m-2 s-2 (kilogram per Ampere-metre squared-second squared)

(T = kg A-1 s-2)
 
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Q should be I*t. I'm sure you knew that.
 
Meir Achuz said:
Q should be I*t. I'm sure you knew that.

My bad ... but I can't edit my thread !
 
Last edited:

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