Energía Cinética
Calcula la energía cinética Ec = ½mv². Despeja masa o velocidad, convierte km/h a m/s y sigue la sustitución paso a paso.
Fórmula principal
KE = (1/2)mv^2
How do you calculate kinetic energy?
For a moving mass treated as a particle, KE = ½ m v². Use mass in kilograms and speed in metres per second; the result is in joules. Rearrange to m = 2 KE / v² or v = √(2 KE / m) when energy is given.
Sobre esta herramienta
La energía cinética (Ec) mide la energía del movimiento; crece con el cuadrado de la velocidad. Aquí verás por qué un pequeño cambio de velocidad altera mucho la energía, con Ec = ½mv² desglosada paso a paso.
Cómo usar esta calculadora
- Elige la variable que quieres despejar y confirma qué valores ya conoces.
- Introduce los datos en unidades coherentes antes de calcular.
- Comprueba si el resultado es físicamente razonable comparándolo con las entradas.
- Usa el desglose paso a paso para ver cómo se aplicó la fórmula.
Ejemplos resueltos
Example 1: 2.0 kg at 3.0 m/s
KE = ½ (2.0)(3.0)² = ½ × 2.0 × 9.0 = 9.0 J. Quick check: ½ × 2 × 9 = 9.
Example 2: find speed from 50 J
A 4.0 kg object has KE = 50 J. v = √(2 × 50 / 4.0) = √25 = 5.0 m/s. Check: ½ (4)(25) = 50 J.
Example 3: convert 36 km/h first
A 0.50 kg ball at 36 km/h → v = 36 / 3.6 = 10 m/s. KE = ½ (0.50)(10)² = 25 J. Skipping the conversion wrongly uses 36².
Preguntas frecuentes
What is the formula for kinetic energy?
For linear motion of a mass, KE = ½ m v². Mass m is in kg, speed v in m/s, and KE in joules. Rearrangements are m = 2 KE / v² and v = √(2 KE / m).
Why is velocity squared in kinetic energy?
The work–energy derivation for accelerating a mass from rest leads to an energy proportional to v². Doubling speed therefore roughly quadruples KE when mass is fixed.
How do I convert km/h for KE problems?
Divide km/h by 3.6 to get m/s before substituting into ½mv². Leaving km/h in the formula produces a hugely inflated joule answer.
Is kinetic energy the same as potential energy?
No. Kinetic energy depends on motion; near-surface gravitational potential energy depends on height via PE = mgh. Falling objects can convert PE to KE, but the formulas use different inputs.
When should I use ½ I ω² instead?
Use rotational kinetic energy when the problem is about spinning about an axis with moment of inertia I and angular speed ω. Otherwise stay with ½ m v² for translation.