Work-Energy Theorem Formula
The Formula
When to use: The total work done on an object is exactly what changes its kinetic energy.
Quick Example
What This Formula Means
The net work done on an object equals the change in its kinetic energy — the bridge between force and motion.
The total work done on an object is exactly what changes its kinetic energy.
Worked Examples
Example 1
easySolution
- 1 The work-energy theorem states: W_{\text{net}} = \Delta KE = \frac{1}{2}mv_f^2 - \frac{1}{2}mv_i^2.
- 2 Net work done: W = Fd = 20 \times 5 = 100 \text{ J}.
- 3 Since v_i = 0: 100 = \frac{1}{2}(4)v_f^2 \implies v_f = \sqrt{\frac{200}{4}} = \sqrt{50} \approx 7.07 \text{ m/s}
Answer
Example 2
mediumWhy This Formula Matters
Often much easier to solve motion problems using energy methods rather than tracking forces.
Frequently Asked Questions
What is the Work-Energy Theorem formula?
The net work done on an object equals the change in its kinetic energy — the bridge between force and motion.
How do you use the Work-Energy Theorem formula?
The total work done on an object is exactly what changes its kinetic energy.
Why is the Work-Energy Theorem formula important in Physics?
Often much easier to solve motion problems using energy methods rather than tracking forces.
What do students get wrong about Work-Energy Theorem?
Only net work changes KE—individual forces may do positive or negative work.
What should I learn before the Work-Energy Theorem formula?
Before studying the Work-Energy Theorem formula, you should understand: work, kinetic energy.