Work-Energy Theorem
The work-energy theorem states that the net work done on an object is equal to the change in its kinetic energy.
Practice This ConceptMain explanation
Teacher explanation
When net work is done on a body, its speed changes. If net work is positive, kinetic energy increases. If net work is negative, kinetic energy decreases. This theorem links force-displacement calculations with motion and energy.
Example
If the net work done on a cart is 80 J, its kinetic energy increases by 80 J.
Simple analogy
Net work changes motion energy.
Common confusion
Students sometimes use total work by one force instead of net work by all forces acting on the object.
Exam tip
Look for the word net. The theorem is about total effective work after considering all forces, not only the applied force.
Answer writing and exam use
1-mark use
Write the exact meaning of work-energy theorem in one clean line.
2-mark use
Define work-energy theorem and add one example or condition.
3-mark use
Explain work-energy theorem, show the method or example, and mention the common mistake.
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