Class 9 Science Exploration Chapter 6 MCQ – How Forces Affect Motion – practice is a smart way to test your understanding of Forces Affecting Motion. The chapter explains force as a quantity with both magnitude and direction, balanced and unbalanced forces, net force and the role of friction. Its main focus is Newton’s three laws of motion, the relation F = ma, the meaning of one newton and the acceleration due to gravity. These objective questions with answers are based on the new NCERT Exploration textbook and include conceptual, graph-based and numerical problems. Regular practice will help you apply the laws of motion confidently in exams.
Class 9 Science Exploration Chapter 6 MCQs with Answer
Class 9 Science Chapter 6 MCQs Set 1
Q1. Which statement correctly describes a force?
[A]. It has direction but no magnitude
[B]. It is measured only in kilograms
[C]. It has both magnitude and direction
[D]. It has magnitude but no direction
Q3. Which instrument can measure the magnitude of a pulling force?
[A]. Stopwatch
[B]. Thermometer
[C]. Measuring cylinder
[D]. Spring balance
Q4. Forces of 10 N and 6 N act to the right on a block. What is their resultant?
[A]. 16 N left
[B]. 4 N left
[C]. 16 N right
[D]. 4 N right
Q5. A block experiences 10 N rightwards and 6 N leftwards. What is the net force?
[A]. 4 N rightwards
[B]. 4 N leftwards
[C]. 16 N rightwards
[D]. 16 N leftwards
Class 9 Science Chapter 6 MCQs Set 2
Q6. The only two forces acting on an object are equal, opposite and along the same line. What is the net force?
[A]. Always increasing
[B]. Twice either force
[C]. Equal to one force
[D]. Zero
Q7. A box slides across a level floor. The forward push equals the opposing friction, and the vertical forces balance. What happens?
[A]. It accelerates forwards
[B]. It must stop immediately
[C]. It continues at constant velocity
[D]. It accelerates backwards
Q8. Why does an object sliding on a rough horizontal surface slow down after the push on it stops?
[A]. Friction continues to oppose its motion
[B]. Gravity always pushes it horizontally
[C]. Its mass disappears
[D]. No forces can act without a push
Q9. With the same starting speed, a sliding object usually travels farther on a surface with less friction because what happens?
[A]. Its speed decreases more slowly
[B]. Its initial position changes
[C]. Its weight becomes zero
[D]. Its mass increases
Q10. What will a moving object do if the net force on it remains zero?
[A]. Stop after a fixed time
[B]. Continue with constant velocity
[C]. Increase its speed continuously
[D]. Move in an increasingly tight circle
Class 9 Science Chapter 6 MCQs Set 3
Q11. What is inertia?
[A]. A force that always increases speed
[B]. The total distance travelled
[C]. The rate of change of temperature
[D]. The tendency to resist a change in rest or uniform motion
Q12. When a net force acts on an object, its acceleration is directed where?
[A]. Always upwards
[B]. Always opposite to the net force
[C]. Always along its existing velocity
[D]. Along the net force
Q13. If the net force on a fixed mass doubles, what happens to its acceleration?
[A]. It becomes four times as large
[B]. It halves
[C]. It stays unchanged
[D]. It doubles
Q14. If the mass doubles while the net force remains unchanged, what happens to acceleration?
[A]. It doubles
[B]. It halves
[C]. It becomes four times as large
[D]. It stays unchanged
Q15. A net force of 12 N acts on a 3 kg object. What is its acceleration?
[A]. 9 m/s²
[B]. 4 m/s²
[C]. 36 m/s²
[D]. 0.25 m/s²
Class 9 Science Chapter 6 MCQs Set 4
Q16. What net force produces an acceleration of 2 m/s² in a 5 kg object?
[A]. 10 N
[B]. 0.4 N
[C]. 2.5 N
[D]. 7 N
Q17. What is the weight of a 2 kg object where g = 9.8 m/s²?
[A]. 19.6 N
[B]. 4.9 N
[C]. 2 N
[D]. 9.8 N
Q18. A weightlifter holds a 30 kg barbell steady. Taking g = 9.8 m/s², what upward force is required?
[A]. 294 N
[B]. 3000 N
[C]. 30 N
[D]. 9.8 N
Q19. Why does a fielder move their hands backwards while stopping a fast ball?
[A]. To increase the ball’s mass
[B]. To make the ball accelerate forwards
[C]. To remove gravity
[D]. To increase stopping time and reduce the force
Q20. How does a landing mat reduce the impact force on an athlete?
[A]. By increasing gravitational acceleration
[B]. By increasing the time over which the athlete stops
[C]. By stopping the athlete instantly
[D]. By making the athlete massless
Class 9 Science Chapter 6 MCQs Set 5
Q21. Which statement expresses Newton’s third law?
[A]. Action and reaction act on one object
[B]. Two interacting objects exert equal and opposite forces on each other
[C]. Forces act only on moving objects
[D]. A larger object always exerts a larger interaction force
Q22. Why do action and reaction forces not cancel the force on either individual object?
[A]. They occur at different times
[B]. They always have different magnitudes
[C]. They act on different objects
[D]. They act in the same direction
Q23. Which force helps propel a person forwards while walking on ordinary ground?
[A]. Forward friction exerted by the ground on the foot
[B]. The foot’s backward force on itself
[C]. Gravity acting horizontally
[D]. An upward force from the air only
Q24. Why does a canoe move forwards when its paddle pushes water backwards?
[A]. The canoe becomes lighter
[B]. Water pushes the paddle forwards
[C]. Water pushes the paddle forwards
[D]. Gravity changes direction
Q25. An inflated balloon is released and expels air backwards. Why does it move forwards?
[A]. The balloon no longer experiences forces
[B]. The escaping air exerts an opposite force on the balloon
[C]. The air has no mass
[D]. Its weight acts forwards
Class 9 Science Chapter 6 MCQs Set 6
Q26. For a rocket to accelerate upwards at lift-off, its upward thrust must do what, neglecting air resistance?
[A]. Equal zero
[B]. Be smaller than its weight
[C]. Exceed its weight
[D]. Act downwards
Q27. Earth and a falling fruit exert equal gravitational forces on each other. Why is Earth’s acceleration unnoticeably small?
[A]. The fruit’s force acts later
[B]. Earth experiences no force
[C]. Earth has an enormously larger mass
[D]. Newton’s laws do not apply to Earth
Q28. During a collision, a loaded cart and an empty cart exert forces on one another. How do these forces compare?
[A]. Both forces are zero
[B]. The loaded cart always exerts the larger force
[C]. They are equal in magnitude and opposite in direction
[D]. The empty cart always exerts the larger force
Q29. Two boxes of masses 2 kg and 3 kg are connected by a light taut string on a frictionless horizontal surface. A horizontal external force of 10 N pulls the system. What is its acceleration?
[A]. 10 m/s²
[B]. 5 m/s²
[C]. 3 m/s²
[D]. 2 m/s²
Q30. When two connected boxes and their string are treated as one system, the tension forces between its parts are classified as what?
[A]. Internal forces
[B]. External gravitational forces
[C]. Unbalanced external forces only
[D]. Forces exerted by the floor
Key Points from Chapter 6 How Forces Affect Motion
- Force is described by both magnitude and direction. Its SI unit is the newton (N), and a spring balance can measure its magnitude.
- Equal and opposite forces on the same object are balanced forces and produce no change in motion.
- When forces act in the same direction, the net force is their sum. When they act in opposite directions, it is their difference, along the larger force.
- Friction acts opposite to the direction of motion. Smoother surfaces have less friction, so objects travel farther before stopping.
- Newton’s first law: an object stays at rest or keeps moving with constant velocity unless a net force acts on it. Galileo’s thought experiments laid the groundwork for this idea.
- Newton’s second law: acceleration is in the direction of the net force, proportional to it and inversely proportional to mass (F = ma).
- One newton is the force that gives a 1 kg mass an acceleration of 1 m s⁻². Gravitational force on an object is F = mg, where g = 9.8 m s⁻².
- Increasing the stopping time reduces the force, which explains a fielder pulling hands back, airbags in cars and landing mats in high jump.
- Newton’s third law: action and reaction forces are equal and opposite but act on two different objects, so they never cancel each other.
- Walking, rowing a canoe, gun recoil and rocket launches are all explained by the third law. For connected objects, a = F ÷ (m₁ + m₂).
Common Mistakes to Avoid in Laws of Motion MCQs
- Thinking a moving object needs a net force to keep moving at constant velocity.
- Treating action-reaction pairs as balanced forces on the same object.
- Assuming equal forces always produce equal accelerations, forgetting the role of mass.
- Forgetting to convert grams to kilograms or km h⁻¹ to m s⁻¹ before using F = ma.
- Missing that a horizontal line on a velocity-time graph means zero net force.
These Class 9 Science Exploration Chapter 6 MCQs connect the laws of motion with everyday situations such as tug of war, pushing a stalled car, catching a cricket ball and the soft landing of Chandrayaan-3’s Vikram lander. Working through them shows how the same three laws explain both simple and complex motions. Attempt the quiz without looking at the answers first, then review each explanation carefully. This habit sharpens your reasoning and prepares you for tricky assertion-reason and numerical questions in exams.
Solve Chapter 6 Exercises Step by Step
After practising these objective questions, the next step is to work through the textbook exercises. Our NCERT Solutions for Class 9 Science Exploration Chapter 6 explain every answer clearly, from net force calculations and velocity-time graph problems to questions on bullets, footballs and connected systems. Combining these solutions with regular MCQ practice gives you a complete grip on “How Forces Affect Motion” and helps you score well in school tests and annual exams.
