Physics

What this covers

• Drawing free-body diagrams for connected systems, inclines, and elevators, then writing Newton's second law separately along each axis
• Splitting projectile and force problems into perpendicular components using sine and cosine, and knowing which component the given angle actually belongs to
• Choosing between kinematics, work-energy, and momentum conservation for a given problem, and recognising when a collision is elastic, inelastic, or perfectly inelastic
• Uniform circular motion and orbital problems: identifying which real force supplies the centripetal acceleration rather than adding a fictitious one
• Series and parallel DC circuits — equivalent resistance, current division, and using Kirchhoff's rules on two-loop circuits
• Wave behaviour: frequency versus period, standing waves on strings and in pipes, interference conditions, and the Doppler shift
• Interpreting position-, velocity-, and acceleration-time graphs, including what slope and area under the curve represent physically

Where learners get stuck

Believing that acceleration is zero when velocity is zero — most visibly at the top of a projectile's flight or at the extremes of an oscillation.

Everyday language treats "stopped" and "no forces" as the same state. The ball is momentarily at rest vertically, so students conclude nothing is acting on it, when gravity is unchanged throughout and the acceleration is at its usual 9.8 m/s² downward.

Treating Newton's third law pairs as if they explain equilibrium — saying the normal force is the reaction to weight.

Both pairs involve two equal, opposite forces, so the distinction gets blurred. Third-law pairs always act on *different* objects; the normal force and weight both act on the same block, which is why the normal force changes in an accelerating elevator while the weight does not.

Assuming kinetic energy is conserved in any collision where momentum is conserved.

The two conservation laws are taught side by side and both appear as "before equals after" equations. Momentum is conserved whenever external forces are negligible, but kinetic energy is only conserved in elastic collisions — otherwise it goes into deformation, sound, and heat.

Thinking current is 'used up' as it moves through resistors in series, so less arrives at the last component.

The word "consumption" and the visible dimming of bulbs suggest current is depleted. What drops across each resistor is potential difference; charge is conserved, so the same current passes through every element of a single loop.

What a session looks like

A session runs as a spoken back-and-forth. You describe the problem you're stuck on — from homework, a past paper, or a topic your teacher moved through too quickly — and Evelyn works through it with you by asking what system you've chosen, what forces act on it, and what quantity is conserved. Expect to be asked to state a free-body diagram in words and to predict an answer's sign or order of magnitude before calculating. Because the format is audio, geometry-heavy diagrams are described rather than drawn, which tends to force the physical reasoning into the open. Sessions can also be used for pre-lab conceptual prep or for reviewing why a marked answer lost credit.

Helpful to know first

• Comfort with algebra II: rearranging multi-variable formulas, solving simultaneous equations, and using the quadratic formula
• Right-triangle trigonometry — sine, cosine, and tangent, plus inverse functions to recover an angle
• Vector addition and resolution into perpendicular components
• Scientific notation, SI units, and unit conversion, including recognising when an answer's units are wrong
• Reading and interpreting slopes and areas on graphs (a first calculus course helps for kinematics but is not assumed)

Questions

Is this for algebra-based or calculus-based physics?

Both. The default treatment is algebra-based, which fits most 11th and 12th grade courses. If your class uses derivatives and integrals for kinematics, work, and Gauss's law, say so at the start of the session and the explanations will use that language instead.

Can Evelyn help with a specific homework problem or past exam question?

Yes. Read the problem aloud or describe the setup, including the given values. The session will focus on setting it up and on the reasoning step you're missing rather than just producing the final number.

My student understands the concepts but loses marks on problems. What helps?

That usually traces to setup rather than concept — an unlabelled axis, a sign error on a component, or reaching for a formula before choosing a system. Sessions spend time on the ordered habit: diagram, axes, known and unknown quantities, then the equation.

How is this different from the astronomy topic?

Physics here deals with the mechanical, electrical, and wave behaviour of everyday objects and the laws behind them. Orbital mechanics and gravitation appear as an application of Newton's laws; stellar structure, cosmology, and observational astronomy are covered in the separate astronomy topic.