🚀 Kinetic energy is the energy an object has because it’s moving. It’s a key concept in the Cambridge IGCSE Physics syllabus and is often asked in exams. Let’s break it down step by step!
Think of a skateboarder zooming down a hill. The faster the skateboarder goes, the more “oomph” they feel. That “oomph” is kinetic energy (KE). It’s the work that would be required to stop the skateboarder from moving.
In physics, kinetic energy is calculated using the equation:
\$E_k = \frac{1}{2} m v^2\$
where:
The result, \$E_k\$, is measured in joules (J).
The velocity appears squared because energy depends on how fast something is moving, and the relationship is not linear. If you double the speed, the kinetic energy becomes four times larger! This is a common point in exam questions, so remember it: speed squared = 4× when speed is doubled.
A toy car of mass \$0.5\,\text{kg}\$ moves at \$4\,\text{m/s}\$. Its kinetic energy is:
\$E_k = \frac{1}{2} (0.5) (4)^2 = 0.25 \times 16 = 4\,\text{J}\$
🎯 Result: 4 joules of kinetic energy.
| Mass (kg) | Speed (m/s) | Kinetic Energy (J) |
|---|---|---|
| 1.0 | 3.0 | 4.5 |
| 0.3 | 6.0 | 5.4 |
| 2.5 | 2.0 | 5.0 |
🎓 Key Points for the Exam:
🔍 Tip: Work through the problems step-by-step and double-check your calculations. Practice will help you spot common mistakes like forgetting the ½ factor or squaring the speed incorrectly.