⚡ WORK-ENERGY THEOREM
PAGE 1 OF 5, THE ENERGY LEDGER
SPEED CHANGE
WORK CHANGES SPEED
To change an object's speed, something must do work on it. In physics, work is not "effort" or "sweat." Work is a precise transfer of energy that happens when a force acts on an object while that object moves through a displacement. Push a shopping cart and it speeds up: your force does positive work, and the cart's kinetic energy rises. Catch a rolling ball and slow it down: your force does negative work, and kinetic energy falls. The work-energy theorem is the bookkeeping rule that links those two ideas. Net work done on an object equals the change in its kinetic energy.
📒 W = ΔKE
The work-energy theorem says net work equals the change in kinetic energy: Wnet = ΔKE = KEf − KEi.
WORK!
POSITIVE WORK
🚀 Force points with the motion
📈 Kinetic energy increases
⚡ Object speeds up
📈 Kinetic energy increases
⚡ Object speeds up
NEGATIVE WORK
🛑 Force opposes the motion
📉 Kinetic energy decreases
🐢 Object slows down
📉 Kinetic energy decreases
🐢 Object slows down