*"Know Thy Enemy" - Sun Tzu.*Undoubtedly the most brilliant military strategist of all time. |

Let's use the quote to learn about the most dreaded subject in school and what Physics is all about. Here we shall discuss the key ideas of Physics, which are (1) concept, (2) variables, (3) comparing, (4) calculation, and (5) explaining.

**1. Concept - know how to describe the term.**

Let's study the term '

**force**'. We learnt in primary school that force is either push or pull. In Physics Form 4, force(

**F**) is defined as a physical quantity which is the product of mass(

**m**) and acceleration(

**a**) (

**F=ma**). So, we can use the formula to define the terms. Other examples:

*a. Momentum = Product of mass and velocity. (p = mv)*

*b. Pressure = Force over area. (P = F/A)*

*c. Potential difference = Product of electrical current and resistance. (V = IR)*

**2. Variables - know the variable relations.**

Next, you should know how to describe the relationship between two variables. We can use either directly or inversely proportional relationship. So, in F=ma, force is directly proportional to acceleration when mass is constant. In turn, force is directly proportional to mass when acceleration is constant.

**3. Compare, compare, compare.**

In Physics question, you are given certain situation for you to compare. For example:

We can see that Situation A has smaller mass than B. Vice versa, Situation A has higher velocity than B. But, both has the same force of 6N.

- which we can conclude that the force in both situation is constant.

- which we can conclude that the force in both situation is constant.

**4. Calculation - Match numbers with formula.**

Calculation is the normal part of Physics question. The key is to carefully read the questions, list the numbers given, and match with formula. Sometimes, the formulas are the combination of those you learnt in previous chapters in both F4 & F5. Example:

**QUESTION:**The crane efficiency is 80%. Calculate the time taken to lift the 20kg load to the height of 5m.**Answer Outline:****5. Explain - Use F4 & F5 Physics Concept Only.**

Finally, in order to explain certain applications in Physics question, you are advised to use the concepts you learnt in F4 or F5. Do not use common sense (even it is correct), because your answer will not be physics-ey enough :-)

*Example: Explaining the features of cooking pan.*

Notice that heat conductor/insulator is technically correct. But we learnt those in F1 before. They are replaced with SHC concept in Chapter 4: Heat in F4.

I hope you guys could grasp what Physics really is. Together we shall defeat and conquer this mutual 'enemy' of ours.

ALL THE BEST!

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