# Physics study guides

Canonical: https://duckyhelper.com/learn/physics/
Updated: 2026-10-01

Plain-language physics guides for high school and AP Physics 1 students. Each one names every symbol and unit, works through real problems step by step, lists the mistakes teachers see most, and ends with practice questions you can check. Every numeric answer on these pages was recomputed in code with g = 9.8 m/s².

- [Unit conversion and significant figures](https://duckyhelper.com/learn/physics/unit-conversion-and-significant-figures/): Convert units with conversion factors, count significant figures, and round answers for multiplication and addition. Rules, worked examples and practice.
- [The kinematics equations](https://duckyhelper.com/learn/physics/kinematics-equations/): The four kinematics equations for constant acceleration, how to pick one, sign rules and free fall. Worked examples with units and 5 practice problems.
- [Projectile motion](https://duckyhelper.com/learn/physics/projectile-motion/): Solve projectile motion by splitting it into horizontal and vertical parts. Horizontal and angled launches, range, max height and 5 practice problems.
- [Newton's laws of motion](https://duckyhelper.com/learn/physics/newtons-laws-of-motion/): Newton's three laws of motion in plain words: inertia, F = ma and action-reaction pairs. Examples with weight, net force and elevators, plus practice.
- [How to draw free body diagrams](https://duckyhelper.com/learn/physics/free-body-diagrams/): Draw free body diagrams step by step: which forces to include, how to label them, ramps and angled pulls, then use F = ma. Worked examples and practice.
- [Friction: static and kinetic](https://duckyhelper.com/learn/physics/friction/): Static vs kinetic friction, the coefficient of friction and how to tell if an object moves. Worked examples with units, a coefficient table and practice.
- [Circular motion and centripetal force](https://duckyhelper.com/learn/physics/circular-motion/): Uniform circular motion explained: centripetal acceleration v²/r, centripetal force, period, flat curves and loops. Worked examples and 5 practice problems.
- [Work and energy](https://duckyhelper.com/learn/physics/work-and-energy/): Work, kinetic and potential energy, the work-energy theorem, conservation of energy and power. Formulas with units, worked examples and practice problems.
- [Momentum and collisions](https://duckyhelper.com/learn/physics/momentum-and-collisions/): Momentum p = mv, impulse, conservation of momentum, and elastic vs inelastic collisions. Worked examples with units and signs, plus 5 practice problems.
- [Density and buoyancy](https://duckyhelper.com/learn/physics/density-and-buoyancy/): Density ρ = m/V, why things float or sink, and Archimedes' principle for buoyant force. Worked examples with units, common mistakes and 5 practice problems.
- [Waves: wavelength, frequency and speed](https://duckyhelper.com/learn/physics/waves/): Wave basics in plain words: wavelength, frequency, period, amplitude and v = fλ, transverse vs longitudinal waves. Worked examples and 5 practice problems.
- [Ohm's law and simple circuits](https://duckyhelper.com/learn/physics/ohms-law-and-circuits/): Ohm's law V = IR, series and parallel resistors, and electric power, explained simply. Worked circuit examples with units and 5 practice problems.

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