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PN Cadet Physics Flashcards
50 question-and-answer cards covering Physics as it is examined in PN Cadet. 24 of them are printed below, taken from across the deck — no signup, no paywall on the preview.
24 sample cards from the Physics deck
Sampled from the end of the deck, so these are different cards from the ones shown on the syllabus page.
Write the conservation of momentum equation for two bodies colliding.
m1 u1 + m2 u2 = m1 v1 + m2 v2, where u are velocities before and v are velocities after the collision.
What is the difference between an elastic and an inelastic collision?
In an elastic collision both momentum and kinetic energy are conserved; in an inelastic collision momentum is conserved but kinetic energy is not (some converts to heat/sound).
What is friction?
A force that opposes the relative motion (or tendency of motion) between two surfaces in contact, acting parallel to the surfaces.
What is the difference between static and kinetic (sliding) friction?
Static friction acts on a stationary object and prevents motion up to a maximum value; kinetic friction acts on a moving object and is usually slightly smaller than maximum static friction.
What is the formula for the force of friction in terms of the coefficient of friction?
F = mu x R, where mu is the coefficient of friction and R is the normal reaction force between the surfaces.
Give two methods of reducing friction.
Lubrication (oil/grease), using ball or roller bearings, polishing/smoothing surfaces, streamlining shapes, or using air cushions.
Give two useful effects (advantages) of friction.
It allows walking without slipping, enables vehicle tyres to grip the road, lets brakes work, and holds nails/screws in place.
What is work done in physics, and what is its formula and SI unit?
Work is done when a force moves an object in its direction: W = F x d (or F d cos(theta) at an angle). SI unit: joule (J).
When is the work done by a force zero even though the force is applied?
When there is no displacement, or when the displacement is perpendicular to the force (cos 90 = 0), e.g. carrying a load horizontally.
What is energy and what is its SI unit?
Energy is the capacity (ability) to do work. Its SI unit is the joule (J).
What is kinetic energy and what is its formula?
Kinetic energy is the energy a body possesses due to its motion: K.E. = (1/2) m v^2.
What is gravitational potential energy and what is its formula?
The energy stored in a body due to its height above a reference level: P.E. = m g h.
State the law of conservation of energy.
Energy can neither be created nor destroyed; it can only be transformed from one form to another, and the total energy of an isolated system remains constant.
For a body falling freely, how do its kinetic and potential energies change?
As it falls, potential energy decreases and kinetic energy increases by an equal amount, keeping the total mechanical energy constant (ignoring air resistance).
What is power, and what is its formula and SI unit?
Power is the rate of doing work or transferring energy: P = Work / time = W/t. SI unit: watt (W), where 1 W = 1 J/s.
What is efficiency and how is it calculated?
Efficiency is the ratio of useful output energy (or power) to total input energy, expressed as a percentage: Efficiency = (useful output / total input) x 100%.
Why can the efficiency of a real machine never be 100%?
Because some input energy is always lost as heat, sound, or to friction, so useful output is always less than total input.
What is electric current, and what is its SI unit?
Electric current is the rate of flow of electric charge: I = Q/t. SI unit: ampere (A), where 1 A = 1 coulomb per second.
What is voltage (potential difference), and what is its SI unit?
Voltage is the work done (energy transferred) per unit charge between two points: V = W/Q. SI unit: volt (V).
What is electrical resistance, and what is its SI unit?
Resistance is the opposition a conductor offers to the flow of current: R = V/I. SI unit: ohm (symbol omega).
State Ohm's Law and its equation.
At constant temperature, the current through a conductor is directly proportional to the potential difference across it: V = I R.
How do you calculate the total resistance of resistors connected in series?
Add them directly: R_total = R1 + R2 + R3 + ... The same current flows through each.
How do you calculate the total resistance of two resistors connected in parallel?
Use 1/R_total = 1/R1 + 1/R2 (so for two resistors R_total = R1 R2/(R1 + R2)). The same voltage is across each.
What is electromagnetism, and what does a current-carrying conductor produce around it?
Electromagnetism is the relationship between electricity and magnetism. A current-carrying conductor produces a magnetic field around it; coiling the wire (solenoid) and adding an iron core makes an electromagnet.
What this deck covers
The Physics deck follows the PN Cadet Physics syllabus — 7 chapters and 21 topics — so questions land on material that is genuinely examinable rather than trivia around it. That works out to roughly 7.1 cards per chapter.
Answers are written to be recallable, not just readable — averaging about 127 characters, which is long enough to carry the reasoning and short enough to say out loud.
A deck like this earns its keep on the second and third pass. Read the syllabus first so you know the shape of the subject, then use the cards to find the specific facts that have not stuck.
Physics flashcards FAQ
How many Physics flashcards are in this PN Cadet deck?
50 cards. This page previews 24 of them, sampled evenly across the deck so you can judge the difficulty before installing anything.
Are these PN Cadet flashcards free?
Yes. The preview here is free to read with no signup, and the full 50-card deck is free inside the Examius app.
What do the Physics cards cover?
They follow the PN Cadet Physics syllabus — 7 chapters and 21 topics — so the questions track what is actually examinable.
How should I use these flashcards?
Read the syllabus first so you know the shape of the subject, then drill the deck. Examius schedules each card with spaced repetition, so cards you keep missing come back sooner and ones you know drift further apart.