# Force and laws of motion MCQ Class 9

MCQ Questions for Class 9 Science Chapter 8, “Force and Laws of Motion,” provide students with a comprehensive assessment of their understanding of fundamental concepts in physics. These multiple-choice questions cover various aspects, such as Newton’s laws of motion, types of forces, and the conservation of momentum. By answering these questions, students can reinforce their knowledge of the principles that govern motion, including the effects of balanced and unbalanced forces, inertia, and the relationship between force, mass, and acceleration. These MCQs serve as a valuable resource for Class 9 students studying force and motion in their science curriculum.

## MCQ Questions for Class 9 Science Chapter 8 Force and laws of motion

Q1. What is a force?
a) A change in shape
b) An object’s speed
c) An effort that changes an object’s state
d) A change in direction

Answer: c) An effort that changes an object’s state

Q2. Which of the following is an effect of force?
a) Changing the color of an object
b) Changing the taste of an object
c) Changing an object’s direction
d) Changing an object’s temperature

Answer: c) Changing an object’s direction

Q3. Which of the following is an example of a push?
a) Plucking the string of a guitar
b) Opening and closing a door
c) Pulling ropes in tug of war
d) Walking

Answer: b) Opening and closing a door

Q4. What is the term for an action that makes something move by tugging or dragging?
a) Push
b) Twist
c) Pull
d) Lift

Q5. When balanced forces act on an object, what happens to the object’s motion?
a) It accelerates
b) It slows down
c) There is no change in motion
d) It moves in the direction of the force with the lowest magnitude

Answer: c) There is no change in motion

Q6. What is the net force when multiple forces act on an object?
a) The sum of all the forces
b) The force with the highest magnitude
c) The average force
d) The force with the lowest magnitude

Answer: a) The sum of all the forces

Q7. What force opposes relative motion between surfaces in contact?
a) Gravitational force
b) Magnetic force
c) Frictional force
d) Electrostatic force

Q8. Which law of motion is also called the Law of Inertia?
a) First Law of Motion
b) Second Law of Motion
c) Third Law of Motion
d) Fourth Law of Motion

Answer: a) First Law of Motion

Q9. What is inertia?
a) A force that opposes motion
b) The tendency of objects to resist changes in their state of motion
c) The measure of an object’s mass
d) A type of friction

Answer: b) The tendency of objects to resist changes in their state of motion

Q10. Inertia depends on which of the following?
a) Color of the object
b) Size of the object
c) Mass of the object
d) Temperature of the object

Answer: c) Mass of the object

Q11. What is the inertia of rest?
a) An object’s tendency to remain in motion
b) An object’s tendency to resist changes in its state of motion
c) An object’s tendency to stay at rest until acted upon by an external force
d) An object’s tendency to move in a straight line

Answer: c) An object’s tendency to stay at rest until acted upon by an external force

Q12. What is the inertia of motion?
a) An object’s tendency to stay at rest
b) An object’s tendency to change direction
c) An object’s tendency to continue in motion until acted upon by a force
d) An object’s tendency to move in a curved path

Answer: c) An object’s tendency to continue in motion until acted upon by a force

Q13. What is momentum defined as?
a) The product of force and time
b) The product of mass and velocity
c) The product of acceleration and time
d) The product of distance and time

Answer: b) The product of mass and velocity

Q14. Which law states that the rate of change of momentum is directly proportional to the applied unbalanced force?
a) First Law of Motion
b) Second Law of Motion
c) Third Law of Motion
d) Law of Conservation of Momentum

Answer: b) Second Law of Motion

Q15. In the context of momentum, what is a vector quantity?
a) A quantity with magnitude only
b) A quantity with direction only
c) A quantity with both magnitude and direction
d) A quantity with no magnitude or direction Answer: c) A quantity with both magnitude and direction

Q16. What is a non-inertial frame of reference?
a) A frame of reference in which Newton’s laws of motion do not hold
b) A frame of reference at rest
c) A frame of reference with constant velocity
d) A frame of reference undergoing acceleration

Answer: a) A frame of reference in which Newton’s laws of motion do not hold

Q17. Which law states that every action has an equal and opposite reaction?
a) First Law of Motion
b) Second Law of Motion
c) Third Law of Motion
d) Law of Conservation of Momentum

Answer: c) Third Law of Motion

Q18. In an isolated system, what can be said about the total momentum?
a) It increases over time
b) It decreases over time
c) It remains constant
d) It depends on external forces

Q19. What is the term for the part of the universe chosen for analysis?
a) Environment
b) System
c) Frame of reference
d) Inertial reference

Q20. What happens in an isolated system with a net external force of zero?
a) Objects within the system move faster
b) Objects within the system move slower
c) Objects within the system remain at rest
d) The total momentum of the system is conserved

Answer: d) The total momentum of the system is conserved

Q21. Which example illustrates an action and reaction pair of forces according to Newton’s Third Law?
a) Pushing a car uphill
b) Throwing a ball against a wall
c) Lifting a heavy box
d) Walking on a flat surface

Answer: b) Throwing a ball against a wall

Q22. What is an accelerometer at rest in a non-inertial frame likely to detect?
a) Zero acceleration
b) Acceleration in the direction of motion
c) Negative acceleration
d) Acceleration opposite to the direction of motion

Q23. Which of the following is an example of an external force on a car moving with constant velocity?
a) Engine running
b) Wind resistance
d) Passenger sitting inside the car

Q24. What is the unit of momentum?
a) Kilograms
b) Meters
c) Kilograms per second
d) Newtons

Q25. What is the net force acting on an object with balanced forces?
a) Zero
b) Equal to the force of gravity
c) Equal to the force of friction
d) Indeterminate

Q26. Which of the following factors does inertia depend on?
a) Shape of the object
b) Color of the object
c) Mass of the object
d) Temperature of the object

Answer: c) Mass of the object

Q27. What does the second law of motion relate to?
a) Mass and acceleration
b) Force and time
c) Distance and time
d) Energy and velocity

Q28. Which law of motion explains the concept of action and reaction forces?
a) First Law of Motion
b) Second Law of Motion
c) Third Law of Motion
d) Law of Conservation of Momentum

Answer: c) Third Law of Motion

Q29. In an isolated system, if the net external force is not zero, what happens to the total momentum?
a) It decreases
b) It remains constant
c) It increases
d) It depends on the mass of the objects

Q30. Which of the following best describes the concept of conservation of momentum?
a) Momentum is always increasing
b) Momentum is always decreasing
c) Momentum is always conserved in isolated systems
d) Momentum depends on the shape of the objects

Answer: c) Momentum is always conserved in isolated systems

Q31. What is the main factor that determines inertia?
a) Color
b) Shape
c) Mass
d) Temperature

Q32. What is the primary cause of frictional force?
a) Magnetism
b) Gravity
c) Contact between surfaces
d) Temperature

Q33. Which of the following is an example of an inertial frame of reference?
a) A car accelerating
b) A car moving at a constant speed
c) A car at rest
d) A car turning at a constant speed

Answer: b) A car moving at a constant speed

Q34. What is the formula for momentum?
a) p = F/m
b) p = ma
c) p = mv
d) p = F/a

Q35. When balanced forces act on an object, what is the overall effect on the object’s motion?
a) It comes to a complete stop
b) It accelerates in the direction of the applied force
c) It moves with constant velocity
d) It changes direction randomly

Answer: c) It moves with constant velocity

Q36. Which of the following is NOT an example of a push?
a) Pushing a swing
b) Kicking a soccer ball
c) Pulling a suitcase
d) Pressing a button

Q37. According to the third law of motion, what happens to the action and reaction forces in a pair?
a) They have different magnitudes
b) They have different directions
c) They have the same magnitude and opposite directions
d) They have the same magnitude and same direction

Answer: c) They have the same magnitude and opposite directions

Q38. In an isolated system, if the net external force is zero, what can be said about the total momentum?
a) It decreases over time
b) It remains constant
c) It increases over time
d) It depends on the shape of the objects

Q39. Which law of motion is often described as “For every action, there is an equal and opposite reaction”?
a) First Law of Motion
b) Second Law of Motion
c) Third Law of Motion
d) Law of Conservation of Momentum

Answer: c) Third Law of Motion

Q40. What is the primary difference between an inertial frame of reference and a non-inertial frame of reference?
a) Inertial frames are at rest, while non-inertial frames are in motion.
b) Inertial frames follow the laws of motion, while non-inertial frames do not.
c) Inertial frames are undergoing acceleration, while non-inertial frames are not.
d) Inertial frames are always in motion, while non-inertial frames are at rest.

Answer: b) Inertial frames follow the laws of motion, while non-inertial frames do not.