Force and Laws of Motion — Class 9 MCQs with Answers
Class 9 CBSE Science · Chapter 5
90 practice questions · 30 Easy · 30 Medium · 30 Hard · Updated
Practise the most important Class 9 CBSE Science questions from Chapter 5, "Force and Laws of Motion". You get 9 timed quizzes made from 90 NCERT-based MCQs, with answers and explanations. The questions are split into 30 Easy, 30 Medium and 30 Hard. Warm up on the basics, then move on to the exam-level questions that set top scorers in CBSE Board exams and the JEE & NEET foundation years apart.
To score well in "Force and Laws of Motion", focus on clear concepts in physics, chemistry and biology basics. Each MCQ here is timed and uses exam-style marking (+4 correct, −1 wrong, 0 skipped). This trains you to stay accurate under time pressure, as real papers need. Every question has a short explanation, so a wrong answer becomes a quick lesson. It is the fastest way to fix gaps before a test.
Use this chapter for focused revision. Start with the Easy set to check your basics on Force and Laws of Motion, then move to Medium and Hard to practise applying them. Your accuracy, streaks and XP save automatically. This chapter also adds to your overall Class 9 Science mastery score. 14 sample questions are solved in full below, with the answer and a worked explanation. Sign in free to start practising.
Key concepts: Force and Laws of Motion (Class 9 Science)
Force changes an object's state of motion, and Newton's three laws state exactly how. This chapter covers inertia, the relationship between force and momentum, action-reaction pairs, and the conservation of momentum in collisions.
- Force
- A push or pull that can change an object's speed, direction or shape; it is a vector quantity.
- Balanced and unbalanced forces
- Balanced forces cancel and leave motion unchanged; only an unbalanced force can start, stop, speed up, slow down or turn an object.
- Newton's first law
- An object stays at rest or in uniform straight-line motion unless acted upon by an unbalanced external force.
- Inertia
- The natural tendency of an object to resist a change in its state of motion; the first law is therefore also called the law of inertia.
Force and Laws of Motion — important questions & MCQs with answers (Class 9 Science)
14 solved questions from this chapter's difficulty levels, each with its answer and explanation. The other 76 are timed and scored when you sign in.
- Q1Easy
Newton's first law of motion is also called the law of:
A.AccelerationB.ConservationC.Action-reactionD.Inertia✓ CorrectAnswer: D. Inertia
Explanation: Newton's first law says a body stays at rest or in uniform motion unless an external force acts on it — this resistance to a change in motion is called inertia, not acceleration or conservation.
- Q2Easy
Momentum p of a body is defined as:
A.m + vB.m/vC.v/mD.mv✓ CorrectAnswer: D. mv
Explanation: Momentum is defined as p = mv (mass × velocity), not m + v or m/v — those don't even carry momentum's correct unit of kg·m/s.
- Q3Easy
SI unit of force is:
A.Newton✓ CorrectB.JouleC.WattD.PascalAnswer: A. Newton
Explanation: The SI unit of force is the newton, defined via F = ma: 1 N = 1 kg × 1 m/s² = 1 kg·m/s². Joule measures energy and watt measures power, not force.
- Q4Easy
SI unit of momentum is:
A.Both N·s and kg·m/s✓ CorrectB.kg·m/sC.N·sD.kg·m²Answer: A. Both N·s and kg·m/s
Explanation: Since F = ma gives 1 N = 1 kg·m/s², and impulse = FΔt = Δp, the units N·s and kg·m/s are equal — both correctly describe momentum, not just one of them.
- Q5Easy
The measure of inertia of a body is its:
A.VolumeB.Mass✓ CorrectC.SpeedD.DensityAnswer: B. Mass
Explanation: Inertia is the tendency to resist a change in motion, and its measure is mass — greater mass needs a greater force for the same acceleration (a = F/m), not volume or density.
- Q6Easy
Momentum is a:
A.Scalar quantityB.Vector quantity✓ CorrectC.Dimensionless quantityD.Constant for all bodiesAnswer: B. Vector quantity
Explanation: Momentum p = mv carries the direction of velocity, making it a vector — two equal masses moving at the same speed in opposite directions have opposite, not equal, momenta.
- Q7Medium
F = ma is the mathematical form of:
A.First lawB.Second law✓ CorrectC.Third lawD.Law of gravitationAnswer: B. Second law
Explanation: F = ma is the mathematical form of Newton's second law: net force equals mass times acceleration.
- Q8Medium
A 5 kg object moves at 4 m/s. Momentum =
A.9 kg·m/sB.20 kg·m/s✓ CorrectC.1.25 kg·m/sD.0.8 kg·m/sAnswer: B. 20 kg·m/s
Explanation: Momentum p = mv = 5 kg × 4 m/s = 20 kg·m/s; adding or dividing mass and velocity instead (giving 9 or 1.25) ignores the correct multiplication formula.
- Q9Medium
Walking is possible because of Newton's:
A.First lawB.Second lawC.Law of inertiaD.Third law✓ CorrectAnswer: D. Third law
Explanation: While walking, the foot pushes the ground backward and, by Newton's third law, the ground pushes the foot forward with an equal and opposite force, propelling the walker ahead.
- Q10Medium
Momentum of a 0.5 kg ball moving at 10 m/s is:
A.50 kg·m/sB.10 kg·m/sC.0.05 kg·m/sD.5 kg·m/s✓ CorrectAnswer: D. 5 kg·m/s
Explanation: p = mv = 0.5 kg × 10 m/s = 5 kg·m/s — multiplying, not dividing (giving 0.05) or scaling up tenfold (giving 50), is what the formula requires.
- Q11Medium
A 10 kg body experiences a net force of 50 N. Its acceleration is:
A.0.2 m/s²B.500 m/s²C.5 m/s²✓ CorrectD.50 m/s²Answer: C. 5 m/s²
Explanation: By Newton's second law, a = F/m = 50 N ÷ 10 kg = 5 m/s². Multiplying F and m instead, giving 500, confuses which way the formula divides.
- Q12Hard
A 2 kg ball accelerates from 0 to 10 m/s in 5 s. Force applied =
A.20 NB.5 NC.10 ND.4 N✓ CorrectAnswer: D. 4 N
Explanation: Acceleration a = Δv/Δt = (10 − 0) m/s ÷ 5 s = 2 m/s². By F = ma, the applied force = 2 kg × 2 m/s² = 4 N.
- Q13Hard
Conservation of momentum applies when:
A.No external force acts on the system✓ CorrectB.External force is non-zeroC.There is frictionD.Bodies are at restAnswer: A. No external force acts on the system
Explanation: Momentum conservation applies strictly to an isolated system — one with no net external force acting on it — since any external force would change total momentum via F = Δp/Δt.
- Q14Hard
A 0.5 kg ball moving at 8 m/s rebounds with velocity 6 m/s in opposite direction in 0.02 s. Average force on the ball:
A.50 NB.100 NC.175 ND.350 N✓ CorrectAnswer: D. 350 N
Explanation: Taking the initial direction as positive, Δp = 0.5×(−6) − 0.5×8 = −3 − 4 = −7 kg·m/s. Average force = |Δp|/Δt = 7 ÷ 0.02 = 350 N — the rebound makes the momentum change bigger, not smaller.
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Start this chapter free →Force and Laws of Motion — FAQs
What are the key concepts in Class 9 Science Force and Laws of Motion?+
Force changes an object's state of motion, and Newton's three laws state exactly how. This chapter covers inertia, the relationship between force and momentum, action-reaction pairs, and the conservation of momentum in collisions. Key ideas include Force, Balanced and unbalanced forces, Newton's first law, Inertia.
What does Class 9 Science Chapter 5 (Force and Laws of Motion) cover on XamBaaz?+
It has 90 NCERT-based MCQs on "Force and Laws of Motion": 30 Easy, 30 Medium and 30 Hard. Together they make 9 timed quizzes, and you never get the same set twice. Every question has an instant explanation. They help you prepare for CBSE Board exams and the JEE & NEET foundation years.
Are these "Force and Laws of Motion" questions free to practise?+
Yes. Sign in with Google to practise "Force and Laws of Motion" free. Full unlimited access is ₹999/year on a launch offer until 1 December 2026. No chapter is charged separately.
How should I revise "Force and Laws of Motion" for the exam?+
Start with the Easy quiz to check your basics, then try Medium and Hard to practise applying them. There are 9 timed quizzes on this chapter, so you can come back for a fresh set instead of one you have seen. Read each explanation, retry the questions you miss, and track your accuracy until it stays high.
Are these "Force and Laws of Motion" MCQs available with answers?+
Yes. 14 sample questions are shown here in full, each with the correct option and a step-by-step "Why" explanation. Sign in free with Google to start practising, with instant scoring.
Is there negative marking in the "Force and Laws of Motion" quizzes?+
Yes. The timed quizzes use exam-style marking: +4 for a right answer, −1 for a wrong one and 0 for a skip. MHT-CET and CBSE board papers have no negative marking. Our mocks for those are scored their way.
What are the important questions from Force and Laws of Motion (Class 9 Science)?+
The questions that matter most test Force, Balanced and unbalanced forces, Newton's first law, Inertia. This page shows 14 solved important MCQs with answers and explanations; all 90 questions on the chapter are available as timed quizzes once you sign in.
Is there an online quiz for Force and Laws of Motion?+
Yes — Class 9 Science Force and Laws of Motion has timed online quizzes at Easy, Medium and Hard levels, with instant scoring and a worked explanation on every question. The first quiz on the chapter is free.