Another Physics chapter from the class 9 NCERT book. Here is a curated list of 35 MCQs from the chapter, covering each topic. In addition, we have also included 10 true & false questions and 10 fill in the blanks questions.
Before going further lets have a look at some of revisable points from the chapter –
- Force changes motion, speed, direction, or shape.
- Force has both magnitude and direction.
- SI unit of force is newton (N).
- Spring balance measures force magnitude.
- Balanced forces produce zero net force.
- Unbalanced forces change an object’s motion.
- Net force determines an object’s motion.
- Friction opposes motion between surfaces.
- Smoother surfaces produce less friction.
- Objects resist motion changes due to inertia.
- Newton’s first law explains inertia.
- Zero net force means constant velocity.
- Newton’s second law: F = ma.
- Acceleration increases with force, decreases with mass.
- Gravity causes acceleration g = 9.8 m/s².
35 MCQ Questions for Class 9 Science: Chapter 6 How Forces Affect Motion
Question 1. What is the SI unit of force?
a) Joule
b) Newton
c) Pascal
d) Watt
Answer:
b) Newton — Symbol is N.
Question 2. Force is a ______ quantity.
a) Scalar
b) Vector
c) Derived
d) Fundamental
Answer:
b) Vector — Magnitude and direction required.
Question 3. Which instrument measures force?
a) Thermometer
b) Barometer
c) Spring balance
d) Ammeter
Answer:
c) Spring balance — Measures force magnitude.
Question 4. Balanced forces have:
a) Same direction
b) Unequal magnitudes
c) Equal and opposite forces
d) No direction
Answer:
c) Equal and opposite forces — Net force becomes zero.
Question 5. When forces are balanced, net force is:
a) 1 N
b) Maximum
c) Zero
d) Infinite
Answer:
c) Zero — Motion remains unchanged.
Question 6. Unbalanced forces produce:
a) No change
b) Motion change
c) Zero acceleration
d) Constant mass
Answer:
b) Motion change — Net force exists.
Question 7. Friction acts:
a) Along motion
b) Opposite motion
c) Upward always
d) Randomly
Answer:
b) Opposite motion — Resists movement.
Question 8. A floating ball experiences:
a) Magnetic force only
b) Gravitational force only
c) Buoyant force only
d) Gravity and buoyancy
Answer:
d) Gravity and buoyancy — Opposite directions.
Question 9. Two forces 10 N and 6 N act same direction. Net force?
a) 4 N
b) 10 N
c) 16 N
d) 60 N
Answer:
c) 16 N — Add same-direction forces.
Question 10. Two opposite forces 10 N and 6 N give net force:
a) 16 N
b) 4 N
c) 60 N
d) 0 N
Answer:
b) 4 N — Difference of magnitudes.
Question 11. Motion depends on:
a) Largest force
b) Number of forces
c) Net force
d) Mass only
Answer:
c) Net force — Resultant matters.
Question 12. Which force acts upward from a surface?
a) Friction
b) Gravitational force
c) Magnetic force
d) Normal force
Answer:
d) Normal force — Perpendicular to surface.
Question 13. Weight of an object is:
a) Magnetic force
b) Electrostatic force
c) Gravitational force
d) Frictional force
Answer:
c) Gravitational force — Earth’s pull.
Question 14. Smaller friction causes object to:
a) Stop sooner
b) Move shorter distance
c) Travel farther
d) Remain stationary
Answer:
c) Travel farther — Slows down gradually.
Question 15. Galileo suggested an object would continue moving if:
a) Force increases
b) Friction removed
c) Mass increases
d) Gravity removed
Answer:
b) Friction removed — Thought experiment.
Question 16. Newton’s first law is also called law of:
a) Momentum
b) Gravitation
c) Inertia
d) Energy
Answer:
c) Inertia — Resistance to change.
Question 17. Inertia means tendency to:
a) Accelerate
b) Resist motion changes
c) Increase force
d) Reduce mass
Answer:
b) Resist motion changes — State remains unchanged.
Question 18. If net force is zero, acceleration is:
a) Infinite
b) Variable
c) One
d) Zero
Answer:
d) Zero — No velocity change.
Question 19. Constant velocity means:
a) Speed changes
b) Direction changes
c) Velocity unchanged
d) Acceleration increases
Answer:
c) Velocity unchanged — Magnitude and direction fixed.
Question 20. Newton’s second law relates force with:
a) Pressure and density
b) Mass and acceleration
c) Work and power
d) Heat and temperature
Answer:
b) Mass and acceleration — Fundamental relation.
Question 21. Mathematical form of Newton’s second law is:
a) F = mv
b) F = ma
c) P = mv
d) W = Fs
Answer:
b) F = ma — Force formula.
Question 22. Acceleration is directly proportional to:
a) Mass
b) Force
c) Density
d) Volume
Answer:
b) Force — More force, more acceleration.
Question 23. Acceleration is inversely proportional to:
a) Force
b) Velocity
c) Mass
d) Distance
Answer:
c) Mass — Heavier objects accelerate less.
Question 24. One newton is the force needed to accelerate:
a) 1 kg by 1 m/s²
b) 1 kg by 10 m/s²
c) 10 kg by 1 m/s²
d) 100 g by 10 m/s²
Answer:
a) 1 kg by 1 m/s² — Definition of 1 N.
Question 25. Acceleration due to gravity is denoted by:
a) a
b) v
c) g
d) m
Answer:
c) g — Earth’s gravitational acceleration.
Question 26. Approximate value of g near Earth is:
a) 1 m/s²
b) 5 m/s²
c) 9.8 m/s²
d) 98 m/s²
Answer:
c) 9.8 m/s² — Nearly constant.
Question 27. Gravitational force on mass m is:
a) ma
b) mg
c) mv
d) m/g
Answer:
b) mg — Weight equation.
Question 28. Acceleration due to gravity depends on:
a) Object mass
b) Object colour
c) Object shape
d) None of these
Answer:
d) None of these — Independent of mass.
Question 29. Momentum equals:
a) Force × Time
b) Mass × Velocity
c) Mass × Acceleration
d) Force × Distance
Answer:
b) Mass × Velocity — Direction follows velocity.
Question 30. While catching a cricket ball, hands move backward to:
a) Increase acceleration
b) Increase force
c) Reduce force
d) Increase momentum
Answer:
c) Reduce force — Increase stopping time.
Question 31. Airbags reduce injuries by:
a) Increasing speed
b) Increasing force
c) Increasing collision time
d) Increasing mass
Answer:
c) Increasing collision time — Lower force produced.
Question 32. Coconut breaks because ground exerts:
a) Small force
b) No force
c) Large force
d) Magnetic force
Answer:
c) Large force — Stops quickly.
Question 33. A moving object without net force will:
a) Stop immediately
b) Accelerate continuously
c) Move with constant velocity
d) Reverse direction
Answer:
c) Move with constant velocity — Newton’s first law.
Question 34. If applied force equals friction, object will:
a) Accelerate
b) Move faster
c) Have zero net force
d) Change direction
Answer:
c) Have zero net force — Forces balance.
Question 35. Direction of acceleration is same as:
a) Mass direction
b) Velocity direction always
c) Net force direction
d) Friction direction
Answer:
c) Net force direction — Key second law idea.
10 True and False Questions for Chapter 6 How Forces Affect Motion
Question 1. Force can change an object’s direction. (True/False)
Answer:
True
Question 2. Balanced forces always cause acceleration. (True/False)
Answer:
False
Question 3. Friction acts opposite to motion. (True/False)
Answer:
True
Question 4. Net force is zero for balanced forces. (True/False)
Answer:
True
Question 5. Inertia is the tendency to resist changes. (True/False)
Answer:
True
Question 6. Newton’s first law is called the law of inertia. (True/False)
Answer:
True
Question 7. Acceleration is inversely proportional to force. (True/False)
Answer:
False
Question 8. A heavier object has greater inertia. (True/False)
Answer:
True
Question 9. The SI unit of force is joule. (True/False)
Answer:
False
Question 10. Gravity causes objects to accelerate toward Earth. (True/False)
Answer:
True
10 Fill in the Blanks Questions for Chapter 6 How Forces Affect Motion
Question 1. The SI unit of force is __________.
Answer:
Newton
Question 2. A force with both magnitude and direction is a __________ quantity.
Answer:
Vector
Question 3. The instrument used to measure force is a __________ balance.
Answer:
Spring
Question 4. Forces that produce zero net force are called __________ forces.
Answer:
Balanced
Question 5. __________ opposes the motion of an object.
Answer:
Friction
Question 6. Newton’s first law is also known as the law of __________.
Answer:
Inertia
Question 7. The mathematical form of Newton’s second law is F = m × __________.
Answer:
a
Question 8. The acceleration due to gravity is represented by __________.
Answer:
g
Question 9. The weight of an object is calculated using m × __________.
Answer:
g
Question 10. An object moving with constant velocity has __________ acceleration.
Answer:
Zero
Question on Match the Columns
Unmatched Columns – Questions
| Column A | Column B |
|---|---|
| (i) Balanced Forces | (a) Opposes motion |
| (ii) Friction | (b) SI unit of force |
| (iii) Newton | (c) Acceleration due to gravity |
| (iv) Inertia | (d) Zero net force |
| (v) g | (e) Resists change in motion |
| (vi) F = ma | (f) Newton’s second law |
Matched Columns – Answer
| Column A | Column B |
|---|---|
| (i) Balanced Forces | (d) Zero net force |
| (ii) Friction | (a) Opposes motion |
| (iii) Newton | (b) SI unit of force |
| (iv) Inertia | (e) Resists change in motion |
| (v) g | (c) Acceleration due to gravity |
| (vi) F = ma | (f) Newton’s second law |
Related Class 9 Physics Chapters
Force questions get easier once motion and energy are clear:
- Describing Motion Around Us MCQs – speed, velocity and acceleration first.
- Work, Energy and Simple Machines MCQs – force applied over a distance.
- Sound Waves MCQs – vibration needs a restoring force.
Practise the numericals
Next chapter: Chapter 7 – Work, Energy and Simple Machines
See all chapters: MCQ Questions for Class 9 Science – All 13 Chapters
