Energy and Power Formulas for STI2D

This page presents crucial formulas and concepts for Terminale STI2D students studying l'énergie et ses enjeux. It covers fundamental relationships in physics and electrical systems that are essential for the Bac STI2D 2024.

The document begins with the basic formula relating force (F), velocity (V), and power (P):

F • V = P (in Watts)

This equation is fundamental in understanding the relationship between mechanical work and power.

Next, it presents the formula for energy:

P × Δt = E

This equation shows how energy is the product of power and time, which is crucial for understanding énergie électrique Terminale STI2D.

The page then moves on to electrical concepts, presenting Ohm's Law:

U = R • I

Where U is voltage (in Volts), R is resistance (in Ohms), and I is current (in Amperes). This formula is essential for solving exercices corrigés physique-chimie terminale sti2d.

Highlight: The document emphasizes the importance of understanding units, showing voltage in Volts (V), current in Amperes (A), and power in Watts (W) or Joules per second (J/s).

The page also includes a section on system efficiency, represented by the Greek letter η (eta):

η = P_sortie / P_entrée

This formula is crucial for calculating the efficiency of energy conversion processes, a key concept in l'énergie et ses enjeux terminale sti2d exercice.

Vocabulary: "Entrée" refers to input, while "sortie" refers to output in the context of energy systems.

Lastly, the document provides some important energy unit conversions:

1 Wh = 3600 J 1 cal = 4.1865 J 1 Tep = 41.8685 GJ 1 kWh = 3600 kJ

These conversions are essential for solving problems related to energy calculations and are frequently used in exercices corrigés physique-chimie terminale sti2d.

Example: To convert 5 kWh to Joules, you would multiply 5 by 3,600,000 (since 1 kWh = 3600 kJ = 3,600,000 J), resulting in 18,000,000 Joules.

The page concludes with a formula for useful power:

P_utile = η × P_absorbée

This equation relates the useful power output to the total power absorbed by a system, taking into account its efficiency. Understanding this concept is crucial for analyzing energy systems in 2I2D cours and preparing for the Bac STI2D 2024.