Science · Lesson 3
Energy & Work
Energy is the capacity to do work. The law of conservation of energy — one of the most fundamental laws in physics — tells us energy cannot be created or destroyed, only transformed.
Quick Check
1. A 2 kg ball moves at 4 m/s. Its kinetic energy is:
8 J
16 J
32 J
4 J
2. Work is done when force is applied:
In any direction
With a component in the direction of motion
Only perpendicular to motion
Only against gravity
3. GPE = mgh. A 5 kg object at 10 m height (g=9.8): GPE =
50 J
490 J
980 J
245 J
4. In a frictionless roller coaster, total mechanical energy is:
Always increasing
Conserved (constant)
Always decreasing
Zero at the top