eapcetpro

EAPCET Physics · Intermediate first year

Physical World

Physical World introduces the scope of physics, the four fundamental forces of nature and the conservation laws that run through the whole subject.

Subject
Physics
Taught in
Intermediate first year
Physics in the paper
40 of 160 questions

Key formulas and results

  • The four fundamental forces: gravitational, electromagnetic, strong nuclear and weak nuclear
  • Relative strength: strong nuclear > electromagnetic > weak nuclear > gravitational
  • The strong nuclear force is the strongest but acts only over about 10−15 m10^{-15}\ \text{m}
  • Gravity is the weakest force but has unlimited range
  • Conserved quantities include energy, linear momentum, angular momentum and charge
  • Approximate relative strengths of the fundamental forces: strong nuclear 1, electromagnetic 10−210^{-2}, weak nuclear 10−1310^{-13}, gravitational 10−3910^{-39}

What this chapter covers

  • Scope and excitement of physics
  • Fundamental forces in nature
  • Nature of physical laws
  • Conservation laws

How it is usually asked

  • Identify a force by its range or relative strength
  • Match scientists with their contributions
  • Questions on conservation laws

Understanding Physical World

Physics tries to explain a huge range of phenomena with a small number of basic laws. Every force you meet in mechanics, such as friction, tension, the normal reaction or the push of a spring, is ultimately one of four fundamental interactions. Apart from weight, which is gravitational, these everyday contact forces are electromagnetic in origin: they come from attraction and repulsion between the charged particles in atoms.

The four forces differ hugely in strength and range. The strong nuclear force binds protons and neutrons but fades beyond about a femtometre. The weak nuclear force drives β-decay. Electromagnetism and gravity both have unlimited range, but gravity is by far the weakest, so it only dominates for very large masses such as planets and stars.

Conservation laws link the whole subject: energy, linear momentum, angular momentum and electric charge stay constant in an isolated system, and each one is connected to a symmetry of nature. EAPCET usually tests this chapter through direct recall, such as ranking the forces by strength, naming the force behind a process, or matching a scientist with a discovery, so a well-organised revision table pays off.

Worked example

EAPCET-style question

Which fundamental force is responsible for the β-decay of a radioactive nucleus?

  1. (1)Gravitational force
  2. (2)Electromagnetic force
  3. (3)Strong nuclear force
  4. (4)Weak nuclear force

Solution

  1. In β-decay a neutron changes into a proton (or a proton into a neutron), emitting an electron or positron and a neutrino.
  2. Changing one type of nucleon into another is not possible with the strong or electromagnetic force.
  3. This change of particle identity is the characteristic process of the weak nuclear force.
  4. So the answer is the weak nuclear force.

Answer: Weak nuclear force

Common mistakes to avoid

  • Assuming the strongest force also has the longest range — the strong nuclear force is the strongest but acts only over about 10⁻¹⁵ m, while gravity and electromagnetism have unlimited range.
  • Listing friction, tension or the normal reaction as separate fundamental forces — they are all electromagnetic in origin.
  • Ranking the weak nuclear force below gravity — the correct order is strong > electromagnetic > weak > gravitational.
  • Saying only mass is conserved in nuclear processes — it is the total mass–energy that is conserved.

How to prepare it

This is a factual chapter — one careful revision of the tables of forces and discoveries is usually enough.

Once the formulas feel familiar, test them the way the exam does: practise Physical World questions chapter-wise, then attempt a full previous year paper to see whether it holds up under a 3-hour timer.

Related Physics chapters

See every chapter in the EAPCET Physics syllabus.

Practise Physical World chapter-wise

Chapter-wise quizzes show exactly which topics in this chapter you still get wrong — before a full paper does.

Frequently asked questions

Is Physical World part of the EAPCET Physics syllabus?
Yes. Physical World is taught in Intermediate first year Physics, and the EAPCET Engineering syllabus is based on the Intermediate first- and second-year syllabus. Check the official notification each year for any changes.
How should I prepare Physical World for EAPCET?
This is a factual chapter — one careful revision of the tables of forces and discoveries is usually enough.
How many Physics questions are there in EAPCET?
40 of the 160 questions in the Engineering paper are Physics, spread across 30 chapters.
What mistakes do students make in Physical World?
Assuming the strongest force also has the longest range — the strong nuclear force is the strongest but acts only over about 10⁻¹⁵ m, while gravity and electromagnetism have unlimited range. Listing friction, tension or the normal reaction as separate fundamental forces — they are all electromagnetic in origin. Ranking the weak nuclear force below gravity — the correct order is strong > electromagnetic > weak > gravitational. Saying only mass is conserved in nuclear processes — it is the total mass–energy that is conserved.