AP Physics 1 / Topic
Work, Energy, and Power
Unit 3 reframes mechanics in terms of energy: work done by forces, kinetic and potential energy, the work-energy theorem, conservation of energy with and without friction, and power.
What the exam asks
- Compute work done by constant forces, including negative work and zero-work cases
- Apply the work-energy theorem to connect net work and speed change
- Use energy conservation across positions (ramps, pendulums, springs, projectiles)
- Account for friction as mechanical energy converted to thermal energy
- Calculate power as the rate of energy transfer
Key formulas and rules
W = F·d·cosθ; area under F-x graph
W(net) = ΔKE
KE = ½mv²; PE(grav) = mgh; PE(spring) = ½kx²
KE1 + PE1 = KE2 + PE2 + f·d
P = W/t = F·v
Question bank breakdown
44
8
12 easy · 24 medium · 8 hard
Skills covered
Every question in the bank comes with a worked explanation, and most add a per-choice breakdown so you learn why each wrong answer is wrong - not just the key.
Sample question
From the free tier of the ScoreMint AP Physics 1 bank - try it, then check the answer.
A block slides across a rough horizontal surface. Its speed decreases from to over a distance of . What is the magnitude of the friction force acting on the block?
- A.
- B.
- C.
- D.
Show answer and explanation
Answer: B. The work-energy theorem states that the net work done on an object equals its change in kinetic energy: . Here, J. The only horizontal force is friction, and its work is (negative because friction opposes displacement). Setting J gives N. The negative sign of confirms energy was removed from the block by friction.
Study tip
Choose energy methods when the question asks about speeds at two positions and forces are messy in between; choose Newton's laws when it asks about forces or acceleration at one instant.