Physics through Problem Solving

Grade 11 & 12 Physics for University-Bound Students

Physics Concepts Students Find Confusing — And How to Actually Understand Them

Every year, the same handful of Grade 11 and 12 physics topics trip up otherwise strong students — not because the ideas are too hard, but because they're genuinely difficult to picture from a textbook diagram alone. Each topic below includes an interactive animation you can play with directly, plus the specific misconception I see most often.

Kinematics & Relative Motion

Relative Velocity & Reference Frames (1D)

A ball walks back and forth inside a moving train. Watch it from the ground and from inside the train — same motion, two different observers, two different answers.

Launch Animation →
Misconception: that velocity is a fixed property of an object, rather than something that depends entirely on who's observing it.

Relative Velocity in 2D — The River-Crossing Swimmer

Adjust a swimmer's heading angle against a river current and watch crossing time and downstream drift trade off in real time.

Launch Animation →
Misconception: assuming the angle that gets you across fastest is the same angle that lands you directly opposite your starting point.

Projectile Motion

Change the launch angle and speed of a projectile and watch horizontal and vertical motion play out completely independently.

Launch Animation →
Misconception: that a faster horizontal launch speed means a shorter time in the air — time of flight depends only on the vertical motion.

Uniform Circular Motion

Adjust radius and speed, then cut the string and watch the object fly off in a straight line — not outward.

Launch Animation →
Misconception: the idea of an outward "centrifugal force" — there is no such force; only inward centripetal force is real.

Energy & Momentum

Conservation of Mechanical Energy — The Swinging Pendulum

Pause the swing at any point and see the exact kinetic/potential energy split, or jump straight to the two extremes with one click.

Launch Animation →
Misconception: that the pendulum has "no energy" at the top of its swing, confusing zero velocity with zero energy.

Momentum & Collisions — Elastic vs. Inelastic

Set masses and speeds, then run the same collision as elastic or perfectly inelastic and compare the before/after numbers directly.

Launch Animation →
Misconception: assuming kinetic energy is always conserved in a collision, the way momentum always is — it isn't, except in the elastic case.

Work & Energy — From Breakfast to a Box on a Ramp

Convert daily food Calories into real mechanical work, then push a box up a ramp at different angles — with or without friction.

Launch Animation →
Misconception: that a steeper ramp needs more total energy to reach a given height — in a frictionless world, height alone determines the energy needed, regardless of angle.

Electricity, Fields & Gravity

Coulomb's Law — Electric Force Between Charges

Change charge magnitude, sign, and distance, and watch the force arrows resize and flip between attractive and repulsive.

Launch Animation →
Misconception: assuming doubling the distance halves the force — the inverse-square relationship means it actually drops to one-quarter.

Gravity — Sun, Earth & Moon

Watch Earth and the Moon orbit together, then remove each body one at a time and see exactly what Newton's First Law predicts happens next.

Launch Animation →
Misconception: that removing the Sun would make Earth simply stop — instead, it would travel in a straight line forever, since gravity was the only thing curving its path.

Modern Physics

Radioactive Decay & Half-Life

Watch 100 individual nuclei decay at genuinely random moments, while the total count still traces the same smooth exponential curve every time.

Launch Animation →
Misconception: thinking a nucleus that has survived a long time is somehow "due" to decay — decay probability has no memory of how long a nucleus has already existed.
Curious how these ideas show up outside the classroom? Visit Why Physics? for a few surprising real-world hooks, or book the free Readiness Assessment to see where you stand.