This 9th class physics chapter 3 online test covers Chapter 3 of the Class 9 Physics course, Dynamics. It has 25 multiple-choice questions, shown one at a time, and it marks itself as soon as you finish. There is no timer and no sign-up. When you press finish you get your score, and every question is shown again with your answer, the correct option and a short explanation of why that option is right. An Urdu medium version of the same test is given further down this page.
What Chapter 3 Covers
The questions are spread across the whole chapter rather than one section, so the test is a fair check of whether you are ready for a class test or the annual paper:
- Newton’s three laws — inertia and the law of inertia, F = ma problems, and why action and reaction do not cancel each other.
- Mass and weight — w = mg, the weight of a 100 g mass, and what changes when an astronaut carries a tool box to the Moon.
- Momentum — p = mv, the momentum of a bullet, collisions between trolleys, and conservation of momentum.
- Friction — static, sliding and rolling friction, why rolling friction is far smaller, and how lubricants and tyre treads change it.
- Terminal velocity — the condition a falling body reaches when the drag balances its weight.
- Safety applications — seat belts, air bags, crumple zones, and why a fielder draws his hands back when catching a ball.
- Contact and non-contact forces, free-body diagrams, and the unification work for which Dr Abdus Salam shared the 1979 Nobel Prize.
Revise These Before You Start
Most marks in this chapter are lost on the same few points. Read through these once before attempting the test:
- F = ma. Watch the units: a mass given in grams must be converted into kilograms first.
- p = mv, and momentum is a vector, so direction matters in collision questions.
- w = mg, with g = 10 m s⁻², so a 5 kg body weighs about 50 N on the Earth and far less on the Moon, while its mass stays 5 kg.
- In a collision, total momentum before equals total momentum after, provided no external force acts.
- Action and reaction are equal and opposite but act on two different bodies, which is exactly why they never cancel out.
- Rolling friction is roughly a hundred times smaller than sliding friction, which is why wheels and ball bearings are used.
How the Test Works
- 25 questions, one at a time, with Next and Previous buttons.
- No timer, so you can work a numerical out on paper before answering.
- Automatic marking the moment you finish.
- Answer review with the correct option and an explanation for every question.
- Retake as many times as you like, and your score is not stored anywhere.
Start the Chapter 3 Online Test
Chapter 3 mixes short numericals with reasoning questions about everyday situations, so you need both the formulas and the explanations. Keep a pen and rough paper beside you: the numerical questions are quick, but they are much easier to get right written down than in your head. Aim for 20 out of 25 or better before you move on to the next chapter.
Chapter 3 Online Test — Urdu Medium
Urdu medium students can attempt the same Chapter 3 test with every question, option and explanation written in Urdu. It behaves exactly like the English test above: 25 questions one at a time, no timer, and a full answer review at the end.
Mistakes Students Make in This Chapter
When you check your answer review, see whether any of your wrong answers came from these. They account for most of the marks lost in this chapter:
- Mixing up mass and weight, especially in questions set on the Moon.
- Forgetting to convert grams into kilograms before using F = ma or p = mv.
- Saying action and reaction cancel each other because they are equal and opposite.
- Treating friction as always harmful, when walking, writing and braking all depend on it.
- Ignoring direction when adding momentum in a collision problem.
What to Do After the Test
Do not close the page as soon as you see your score. Read the explanation under every question you got wrong, then open that topic in your textbook and work through the solved example beside it. Write the questions you missed on a single sheet and attempt the test again the next day: the second score tells you what you have actually learned, while the first only tells you what you recognised. If you scored below 15, work through the chapter again before moving on, because the later chapters in Physics build directly on this one.
Frequently Asked Questions
Why do action and reaction forces not cancel each other?
Because they act on two different bodies. When you push a wall, your force acts on the wall and the wall’s force acts on you. Forces only cancel when they act on the same body.
What is terminal velocity?
It is the constant velocity a falling body reaches when the upward drag force becomes equal to its weight. The net force is then zero, so the body stops accelerating and falls at a steady speed, which is what happens to a paratrooper once the parachute opens.
Does an object weigh the same on the Moon as on Earth?
No. Mass stays the same everywhere, but weight is mg and the Moon’s gravitational field strength is about one sixth of the Earth’s, so a 6 kg tool box weighs about 60 N on Earth and only about 10 N on the Moon.
Related Class 9 Physics Resources
Work through the Chapter 3 exercise short questions for written practice. The Chapter 3 constructive questions cover the longer, reasoning-based answers. You can also browse all Class 9 Physics exercise short questions and constructive questions, or open the Class 9 Physics section, which brings notes, test papers, online papers, guess papers and past papers together chapter by chapter.