Energy⏱ 4 min read

Kinetic Energy

KE = ½mv²

📖 What is Kinetic Energy?

Kinetic energy is the energy an object possesses due to its motion. Any moving object — a rolling ball, a flying plane, or a speeding car — has kinetic energy. The faster it moves or the more massive it is, the greater its kinetic energy.

KE = ½ × m × v²

🔤 What Each Variable Means

KE
Kinetic Energy (Joules, J)The energy of motion. 1 J = 1 kg·m²/s²
m
Mass (kilograms, kg)The amount of matter in the moving object
v
Velocity (metres per second, m/s)The speed of the object. Note: velocity is squared, so doubling speed quadruples KE!

📝 Step-by-Step Example

A 2 kg ball rolls at 5 m/s. What is its kinetic energy?

1
Identify known valuesm = 2 kg    v = 5 m/s
2
Write the formulaKE = ½ × m × v²
3
Square the velocity firstv² = 5² = 25 m²/s²
4
Substitute and calculateKE = 0.5 × 2 × 25 = 25
Answer: KE = 25 J

The ball has 25 Joules of kinetic energy.

🧮 Interactive Calculator

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💡 Key Insight: Velocity Squared

Because velocity is squared, doubling the speed of an object quadruples its kinetic energy. This is why high-speed crashes are so much more dangerous than low-speed ones.

Speed × 2 → KE × 4
Speed × 3 → KE × 9
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🎯 Quick Fact

The term "kinetic" comes from the Greek word "kinētikos" meaning "of motion."