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Why is A Level Physics So Hard?

A Level Physics will be harder because assumptions and simplifications are gradually being removed to resemble real-world scenarios.

Compared to O Level, there is a steep increase in the learning curve.

This is only natural.

Having now graduated from the top 20% of the O Level cohort, the syllabus is now made much tougher to further differentiate among all of you.

Simplification of Real World

Learning new concepts always start by trimming away the complexities.

For Physics, one of the items that complicate the maths will be friction.

So O Level Physics and to a certain extent A Level Physics always assumes a frictionless world.

Objects in motion, in the absence of friction, have to move forever.

But this comes as a cost as such assumptions does not gel very well with the real world.

On one hand you are told Physics aim to help you understand our physical world.

Yet on the other, you have to fight to resist the idea that you are forced to study something that appears to be blatantly incorrect.

Here are some reasons:

Misleading stories

Fake narratives like the famous Galileo’s experiment where he dropped a feather and cannonball simultaneously and found both to land on the ground at the same time confuses many Physics students.

“I thought there is supposed to be air resistance? How could this happen, when the terminal velocity of the feather is lower than that of a cannonball?”

Gravitational energy formula

In A Level you will learn that GPE = mgh is nothing but a simplification when g is assumed to be constant.

Where gravitation field strengths changes in vast distances the GPE = mgh formula will break down and cannot be used.

More Complex Concepts

As you progress in your education, more complicated concepts being introduced.

Concept of field

The concept of fields, such as the gravitational field, magnetic field, and the electric field is confusing because you cannot see them directly.

However, we can experience them either directly, through the effects of gravity or indirectly where you observe things move at distance from a force.

Free-body diagram

Learning to draw free-body diagrams can be a pain because you need to account for all the forces and their directions.

Students also find it hard to relate that frictional and normal contact force are components of reaction force.

Furthermore, it is also hard for some to understand Newton’s Third Law where the action-reaction forces do not cancel each other out, since we cannot feel the force we impact on other objects.

Quantum physics

The need to start introducing the 21st century’s Quantum Physics may be repulsive for some when it is juxtaposed against 17th century’s Newtonian Physics in the same syllabus.

Imagine you have been rigorously studied Newtonian Physics and finally accepted it despite living in a world where friction exists, only to find out that it is not the gold standard for Physics.

New concepts such as wave-particle duality where waves can behave like particles and vice versa, or mass-energy equivalence, where lost in mass can produce energy are mind-blowing.

You have learned first about magnetism, then electricity, and finally the confluence of both leading to the phenomenon of electromagnetism.

Yet we should not avoid understanding this topic because the discovery of electromagnetism vastly improves our standards of living.

So in some sense, students should pray Quantum Gravity, linking quantum and gravity will never be established.

The Need to Handle Mathematics

Students often complain about the presence of mathematics in Physics, such as Calculus topics like differentiation and integration.

The frustration arises because they are not adequately trained on techniques such as chain rule when used in the derivation of force as the rate of change of momentum.

So students tend to memorize the laws line by line rather than attempting to derive the final formula through derivation from first principles.

Mathematics as a subject exists in the compilation of common techniques to help solve problems in sciences.

For example, did you know Fleming’s Left Hand and Right-Hand rule exists from the cross product?

The cosine theta in W = F s cosθ exists because of the dot product.

Same for the magnetic flux formula Φ = B A cosθ.

Formula list like this might only help to a certain extent.

Context-Dependent Sign Conventions

Negative signs

Negative signs when used in Physics can be extremely confusing.

On one hand, when used in vectors they can indicate directions.

At times, they are employed to describe attractive forces, as in the case of gravitational forces.

Yet it can also be used to mean a decrease in scalar quantities such as energy.

No wonder A Level Physics can be confusing.

Negative acceleration

The term “negative acceleration” is used in some Physics textbooks.

But the use of this term can mean different things when used in different contexts.

If you have set right as the positive convention, negative acceleration can mean deceleration in the right direction, or it can mean accelerating in the left direction.

In one case you are gaining speed while in another, you are losing speed.

1st law of thermodynamics

The 1st Law of Thermodynamics can be very confusing to some due to the way work is done W is defined. Should it be work is done on the system, or work done by the system.

Also, when will the negative sign be attached to W?

That effectively means there could be four permutations as to how it can be interpreted.

By the way, Wikipedia defines the first law to be U = Q – W,

where W is the work done by the system, adding to more confusion.

The correct way would be to think of how internal energy can be increased through the input of thermal energy plus work done on the system.

Staying Conventional

The part about having discovered that direction for conventional current is actually “wrong” can make some feel uncomfortable. Such as:

Temperature scale

Similarly, students tend to feel uncomfortable on the now preferred use of the Kelvin scale over Celsius, despite the widespread use of Celsius or Fahrenheit.

Electromotive force

What exactly is the electromotive force? A force, or an energy source?

Legacy terms that can lead to so much confusion should be deprecated.

Heat energy

Just like there is no current energy, there should not be heat energy.

Make a conscious effort to use thermal energy instead.

Formalized Explanations

Because textbooks tend to be formal, certain concepts can be hard to understand.

It will be so much easier to explain why voltages in the parallel circuit have to be the same by illustrating the concepts differently.

It would be easier to understand that voltages are the quantity of energy carried by one Coulomb of charge and that any charges could only take one of the branching paths to travel around the circuit.

Since all the charges are pumped up by the e.m.f. with the same energy initially, charges in all the branches must have the same voltages.

To explain why adding a resistor in parallel, no matter how large, always decreases the effective resistance.

Say you are queuing up in a fast-food restaurant with only an ordering counter and a super long queue.

Despite manning by a super-efficient staff, the queue does not seem to move.

If a second counter is open now but manned by a newer and much slower staff, would you agree that this will still help in shortening the overall waiting time, albeit only by a little?

Hence, putting another resistor (even one with super high resistance) in parallel to the first always decreases the overall resistance.

P. S.

If you do want your parents to know your pain in understanding Physics, make sure they read this.

Your friends will want a copy of this article, make them ask for it.