## Class 9 Science Case Study Questions Chapter 9 Force and Laws of Motion

Case study Questions in Class 9 Science Chapter 9 are very important to solve for your exam. Class 9 Science Chapter 9 Case Study Questions have been prepared for the latest exam pattern. You can check your knowledge by solving Class 9 Science Case Study Questions Chapter 9 Force and Laws of Motion

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In CBSE Class 9 Science Paper, Students will have to answer some questions based on Assertion and Reason. There will be a few questions based on case studies and passage-based as well. In that, a paragraph will be given, and then the MCQ questions based on it will be asked.

# Force and Laws of Motion Case Study Questions With Answers

Here, we have provided case-based/passage-based questions for Class 9 Science Chapter 9 Force and Laws of Motion

Case Study/Passage-Based Questions

Case Study 1: The sum of the momentum of the two objects before the collision is equal to the sum of momentum after the collision provided there is no external unbalanced force acting on them. This is known as the law of conservation of momentum. This statement can alternatively be given as the total momentum of the two objects is unchanged or conserved by the collision. The Law of conservation of momentum is applicable to the system of particles. Answer the following questions.

(i)Law of conservation of momentum is applicable to

(a) A system of particles

(b) Only for 2 particles

(c) Only for 1 particle

(d) None of the above

Answer: (a) A system of particles

(ii) Law of conservation of momentum holds good provided that

(a) There should be external unbalanced force acting on particles

(b) There should not be any external unbalanced force acting on particles

(c) No internal forces acting on particles

(d) None of the above

Answer: (b) There should not be any external unbalanced force acting on particles

(iii)The total momentum of the two objects when collision occurs is

(a) Changed

(b) Remains conserved

(c) Become zero

(d) None of the above

(iv) State law of conservation of momentum.

Answer: The sum of momentum of the two objects before collision is equal to the sum of momentum after the collision provided there is no external unbalanced force acting on them. This is known as the law of conservation of momentum. This statement can alternatively be given as the total momentum of the two objects is unchanged or conserved by the collision.

(v) If action and Reaction are equal in magnitude and opposite in direction then why they do not cancel each other?

Answer: Action and Reaction are equal in magnitude and opposite in direction but they do not cancel each other because they are not action on sane object. As these forces are acting on different object hence produces different acceleration and does not cancel each other.

Case Study 2: The third law of motion states that when one object exerts a force on another object, the second object instantaneously exerts a force back on the first. These two forces are always equal in magnitude but opposite in direction. These forces act on different objects and never on the same object. It is important to note that even though the action and reaction forces are always equal in magnitude; these forces may not produce accelerations of equal magnitudes, this is because each force acts on a different object that may have a different mass. The two opposing forces are also known as action and reaction forces. Answer the following questions.

(i) Action reaction forces are always

(a) Equal and in the same direction

(b) Equal and in the opposite direction

(c) Unequal and in the same direction

(d) None of the above

Answer: (b) Equal and in the opposite direction

(ii) Which of the following is correct about action reaction forces?

(a) They act on different objects

(b) They are equal in magnitude and opposite in direction

(c) Both forces acted on different object simultaneously

(d) All the above

(iii) State third law of motion

Answer: The third law of motion states that when one object exerts a force on another object, the second object instantaneously exerts a force back on the first. These two forces are always equal in magnitude but opposite in direction. These forces act on different objects and neveron the same object.

(iv) Give 5 examples of third law of motion

Answer: Examples of third law of motion are Swimming or rowing a boat. •Static friction while pushing an object. •Walking. •Standing on the ground or sitting on a chair. •The upward thrust of a rocket. •Resting against a wall or tree.

Case Study 3:

Force is a push or pull that can change the state of motion of an object. According to Newton’s first law of motion, an object at rest will remain at rest, and an object in motion will continue moving with a constant velocity in a straight line unless acted upon by an external force. This is known as the law of inertia. Newton’s second law of motion states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. Mathematically, this can be expressed as F = ma, where F is the force, m is the mass of the object, and a is the acceleration produced. Newton’s third law of motion states that for every action, there is an equal and opposite reaction. This means that whenever an object exerts a force on another object, the second object exerts an equal and opposite force on the first object. Understanding the concepts of force and the laws of motion helps us explain the behavior of objects and the factors that influence their motion.

What is force?
a) A change in the state of motion of an object
b) A push or pull that can change the state of motion of an object
c) The mass of an object
d) The velocity of an object
Answer: b) A push or pull that can change the state of motion of an object

What does Newton’s first law of motion state?
a) An object at rest will remain at rest, and an object in motion will continue moving with a constant velocity in a straight line unless acted upon by an external force.
b) The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass.
c) For every action, there is an equal and opposite reaction.
d) The force exerted by an object is equal to its mass multiplied by its acceleration.
Answer: a) An object at rest will remain at rest, and an object in motion will continue moving with a constant velocity in a straight line unless acted upon by an external force.

What is Newton’s second law of motion?
a) An object at rest will remain at rest, and an object in motion will continue moving with a constant velocity in a straight line unless acted upon by an external force.
b) The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass.
c) For every action, there is an equal and opposite reaction.
d) The force exerted by an object is equal to its mass multiplied by its acceleration.
Answer: b) The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass.

What is Newton’s third law of motion?
a) An object at rest will remain at rest, and an object in motion will continue moving with a constant velocity in a straight line unless acted upon by an external force.
b) The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass.
c) For every action, there is an equal and opposite reaction.
d) The force exerted by an object is equal to its mass multiplied by its acceleration.
Answer: c) For every action, there is an equal and opposite reaction.

How do the concepts of force and the laws of motion help us?
a) Explain the behavior of objects and the factors that influence their motion.
b) Calculate the speed of objects.
c) Classify objects into different categories.
d) Determine the position of objects.
Answer: a) Explain the behavior of objects and the factors that influence their motion.

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