How to Learn Physics Quickly and Correctly

Physics becomes easier when you stop collecting formulas and start asking what changes, what causes the change and what measurements can test the explanation. In this eduKateSG Science Quick Notes lesson, we learn Physics quickly and correctly through a toy car, everyday forces, movement and simple speed calculations. You will learn a short method, see clear worked examples and check your understanding with questions you can answer without a textbook.

Observe: say exactly what the object does before explaining it.
Identify: name the forces, energy transfers or measurable quantities involved.
Connect: explain what causes a change in speed, direction or state.
Calculate: write the correct relationship, values and units when needed.
Check: test a different example instead of memorising one sentence.

Teaching step 1 — watch what happens. Imagine giving a small toy car a short push across a flat floor. It moves forward, slows down and finally stops. Write that as an observation first. You have not yet explained why it stops. Now imagine rolling the same car onto a rough mat: it often slows down more quickly. That comparison gives you a question worth investigating: how does the surface influence the car’s motion?

Teaching step 2 — name the process. During the push, your hand can exert a forward force. Once your hand leaves the car, you are no longer pushing it, but the car can continue moving. Friction and other resistive effects act against its motion, which can make it slow down. A moving object does not need a continuous forward push just to keep moving; a net force is needed to change its motion. This distinction is one of the most useful Physics ideas to learn early.

Teaching step 3 — draw, explain and transfer. Sketch the car with arrows: weight downward, support from the floor upward, and friction opposing the car’s movement. Add a forward applied-force arrow only while the car is being pushed. Now change the situation: a rolling suitcase slows down when you stop pulling it. The object looks different, yet the same force-and-motion reasoning helps. If you can explain both cases, you are learning the idea rather than the picture.

Use the Physics three-question method

What changed? Position, speed, direction, temperature, brightness or another measurable quantity?
What could cause it? A net force, transfer of energy, interaction between materials or a different circuit arrangement?
What evidence would distinguish explanations? A distance, time, temperature reading, diagram or controlled comparison?

For the toy car, the observed change is decreasing speed. The explanation involves a net resistive force. A way to investigate is to use the same car and comparable starting conditions on different surfaces and measure how far it travels. Avoid saying that roughness is the only possible difference if the starting push also changes.

Understand force without the common shortcuts

A force is an interaction that can change an object’s motion or shape. In basic mechanics, a non-zero resultant (net) force changes velocity, which means changing speed, direction or both. A balanced force situation does not mean that an object must be stationary. It can also mean that an object is moving in a straight line at constant speed. That is why “there is a force because it is moving” is not a reliable rule.

Consider a book resting on a table. Gravity pulls it down and the table exerts an upward support force. The book does not accelerate through the table because those vertical forces balance. If you give the book a sideways push and it begins moving, consider both your push and friction when discussing what happens.

Learn speed with meaning, not a naked formula

Average speed = total distance travelled ÷ total time taken. Suppose a cyclist travels 120 metres in 30 seconds. Average speed = 120 ÷ 30 = 4 metres per second (4 m/s). This tells you the distance travelled per unit time on average; it does not tell you whether the cyclist maintained 4 m/s throughout the journey.

Now compare a 120-metre journey completed in 60 seconds. Average speed = 2 m/s. The distance is the same, but taking longer produces a lower average speed. To avoid mistakes, identify which quantity is given and which one is required. Write the relationship before substituting values.

Distance: how much ground was covered, measured in metres (m) or kilometres (km).
Time: how long the journey took, measured in seconds (s), minutes or hours.
Speed: distance travelled per time taken, for example m/s.
Check: use matching units. If distance is in kilometres and time is in hours, the answer is in km/h.

Force and energy are not the same thing

The car’s movement is associated with kinetic energy. Friction can transfer energy into internal energy of the car, ground and surroundings, as well as sound. It is inaccurate to say that the car stops simply because “its force runs out.” Force describes an interaction; energy is a quantity that can be stored and transferred. In Physics, using the right word helps you give the right reason.

An everyday example is rubbing your hands. Friction acts between their surfaces while energy from your movement is transferred into warming the hands. Naming both the interaction and the transfer leads to a clearer explanation than saying “friction creates heat from nothing.”

Read a Physics diagram correctly

Force arrows: look for the direction of each force, and do not assume every arrow has the same size.
Motion arrows: check whether they show velocity, acceleration, travel direction or something else.
Distance-time graphs: identify the axes before saying what a line means.
Circuit diagrams: trace the complete conducting path and check whether the switch is open or closed.

An arrow is a symbol, not a universal meaning. A labelled force arrow is not the same as a travel-direction arrow. If the question gives a key, follow that key. It is often worth one extra moment to draw a tiny arrow legend before explaining the system.

Three mistakes to stop making

“A moving object must have a forward force.” Repair: distinguish motion from a change in motion; ask about the resultant force.
“Friction always makes an object stop immediately.” Repair: friction can slow movement over time; what happens depends on the forces and conditions.
“Four metres per second means exactly four metres every second.” Repair: the calculated average speed does not prove that instantaneous speed was constant.

Quick Physics practice

1. A toy car is moving after a short push ends. Does its movement prove that a forward hand force is still acting?
2. Why may a rolling car slow down on a rough surface?
3. A learner walks 90 m in 30 s. What is the average speed?
4. A learner travels 150 m in 50 s. What is the average speed, including units?
5. A book is resting on a table. Name two forces acting vertically on it.
6. Can balanced forces act on an object that is already moving?

Answers and explanations

1. No. The hand is no longer applying a force after contact ends; the car can continue to move.
2. Friction and other resistive forces can produce a net force opposing its motion, reducing speed.
3. 90 ÷ 30 = 3 m/s.
4. 150 ÷ 50 = 3 m/s.
5. Weight downward and the table’s support force upward.
6. Yes. If velocity is constant in a straight line, the resultant force can be zero.

Seven-minute Physics revision

Minute 1: choose one question about a real object or event.
Minute 2: write the observation without guessing.
Minutes 3–4: draw the forces or energy transfer and explain the main cause.
Minute 5: calculate one relevant quantity if the question needs it.
Minute 6: try a changed example without notes.
Minute 7: check one explanation and correct its first inaccurate word or step.

A routine is meant to focus your attention, not make a difficult question feel rushed. If the cause is unclear, use a longer explanation or ask your teacher to check the diagram. Scientific accuracy matters more than finishing within a timer.

Frequently asked questions

Do I have to memorise Physics formulas?

You need to know the relevant relationships expected at your school level, but understanding the quantities comes first. Practise deciding which formula fits and checking the units, rather than substituting numbers into every formula you can remember.

What if I cannot draw the force arrows?

Begin by naming what is touching the object and what acts at a distance, such as gravity. Decide which force each interaction creates. The diagram then becomes a simple picture of the explanation, not a drawing you must memorise.

Continue learning with Science Quick Notes

For deeper explanations, visit the eduKateSG How X Works Hub. Use the detailed pages when you need more examples; use these Quick Notes when you want to practise a single idea accurately.

Remember: Observe → identify interactions → explain the change → measure → check. Physics is easier when every symbol has a meaning.