Energy

Overview

Engineering reference data for Energy in dynamics.

Key Formulas

Newton's Second Law

$F = ma$

Force = mass × acceleration.

Kinetic Energy

$E_k = \frac{1}{2}mv^2$

Energy of motion.

Momentum

$p = mv$

Mass × velocity.

Work

$W = Fd\cos\theta$

Force × displacement × cos(angle).

Variables

Energy Efficiency

Energy efficiency is the ratio of useful energy output to energy input, often expressed as a percentage:

$$\mu = \frac{E_o}{E_i}$$

where:

• $\mu$ = energy efficiency
• $E_o$ = useful energy output
• $E_i$ = energy input

Example Calculation

A lift exerts a force of $100\ \text{N}$ to move a mass $10\ \text{m}$ upward. If the input energy is $1500\ \text{J}$, its efficiency is:

$$\mu = \frac{(100\ \text{N}) \times (10\ \text{m})}{1500\ \text{J}} = 0.67 = 67\%$$

Forms of Energy

Energy can be converted between various forms, including:

• Mechanical energy
• Heat or thermal energy
• Electrical energy
• Chemical energy
• Nuclear energy
• Light energy

References

• Original Source