NCERT Class 9 Science — Chapter 2: Force and laws of motion

Consider the following statements regarding ‘balanced forces’ acting on an object: 1. They always result in the object coming to a state of rest. 2. They do not change the state of rest or of motion of an object. 3. If an object is pulled from opposite sides with equal forces, the net force acting on it is zero. Which of the statements given above is/are correct?

The phenomenon of gun recoil is a direct consequence of:

A motor vehicle with a dead battery requires a continuous push to start rather than a sudden jerk. This is best explained by the fact that:

With reference to the motion of a bicycle, consider the following statements: 1. When pedalling stops, the bicycle slows down solely due to the absence of the pedalling force. 2. To keep the bicycle moving at a uniform velocity, the applied force must balance the frictional force. 3. An object moves with a uniform velocity when the pushing force is greater than the frictional force. Which of the statements given above is/are correct?

Consider the following everyday experiences: 1. Dust coming out of a carpet when beaten with a stick. 2. Leaves getting detached from a tree when shaken vigorously is unrelated to the property of inertia. 3. A coin falling into a tumbler when the card below it is flicked. Which of the above can be explained by the Law of Inertia?

With reference to Newton's Third Law, action and reaction forces act:

The magnitude of impact produced by a moving object upon collision primarily depends on:

Although the action and reaction forces between a gun and a bullet are equal, the gun recoils with a much lower acceleration because:

Luggage kept on the roof of a bus is secured with a rope primarily to:

During a collision between a heavy truck and a light car, which of the following is true regarding the forces experienced?

When a constant unbalanced force is applied to a body of fixed mass, the body moves with:

In which one of the following scenarios is the magnitude of the applied force the largest?

If an object is moving with a certain velocity and all unbalanced forces acting on it are suddenly removed, the object will:

What is the physical reason for a cricket fielder pulling his hands backwards while catching a fast-moving ball?

With reference to action and reaction forces, consider the following statements: 1. They act on the same object. 2. They are always equal in magnitude. 3. They always act in the same direction. Which of the statements given above is/are correct?

In order to walk forward on a road, a person must push the ground in which direction?

Which one of the following statements correctly describes the relationship between force and acceleration?

The backward movement of a boat when a sailor jumps out of it is an example of:

Newton's First Law of Motion is alternatively referred to as the:

The recoil of a gun after firing a bullet is best explained by:

With reference to the First and Second Laws of Motion, consider the following statements: 1. The First Law of Motion can be mathematically deduced from the Second Law of Motion. 2. The First Law is a special case of the Second Law where the applied force is infinite. Which of the statements given above is/are correct?

If a net unbalanced external force on an object is zero, which of the following is possible? 1. The object is at rest. 2. The object is moving with a non-uniform velocity. 3. The object has zero acceleration. Which of the statements given above is/are correct?

Which one of the following phenomena is a direct application of Newton's Third Law of Motion?

If a force is applied to an object but its momentum remains constant, which one of the following is the most likely inference?

Consider the following statements regarding the nature of friction: 1. Friction always acts in the direction opposite to the relative motion. 2. The force of friction is independent of the nature of the two surfaces in contact. 3. Friction cannot be eliminated completely in practical situations. Which of the statements given above is/are correct?

According to the laws of motion, a change in the speed or direction of an object requires:

A bullet of relatively small mass can cause fatal injury. This is primarily attributed to its:

If a heavy box remains stationary despite a pushing force being applied, it implies that:

The physical property known as 'inertia' refers to:

Consider the following statements about the "natural state" of an object: 1. Early scientists believed that uniform motion was the natural state of an object. 2. Galileo and Newton established that motion requires no cause to continue if friction is absent. 3. An unbalanced external force is required to change the state of uniform motion. Which of the statements given above is/are correct?

In the context of Galileo’s experiments with inclined planes, what would happen to a marble if the slope of the second plane is reduced to zero?

Which one of the following statements best describes Newton's Second Law of Motion?

What does the term 'momentum' refer to in physics?

When a tray holding a water-filled tumbler is turned or rotated quickly, the water tends to spill. This phenomenon is best explained by:

In the derivation of Newton's Second Law ($F = kma$), the value of the proportionality constant $k$ becomes unity (1) because:

A karate player breaks a slab of ice with a single blow. This is possible because:

In a high jump athletic event, athletes are made to fall on a cushioned bed or a sand bed. The primary reason for this is to:

Which one of the following correctly defines the unit of force known as 'Newton'?

If mass is measured in kilograms and acceleration in meters per second squared, the resulting unit of force is:

If an object is undergoing acceleration, which one of the following conditions must be true?

The direction of the change in momentum of an object is:

In the context of Newton's Third Law, which one of the following statements regarding 'action' and 'reaction' is correct?

Action and reaction forces are equal in magnitude but often produce different accelerations. This is primarily because:

When a football player kicks a ball, the force exerted on the ball is supplied by:

A cricket ball rolling on level ground eventually comes to a stop because:

According to the Law of Conservation of Momentum, in an isolated system:

The 'Law of Inertia' is applicable to:

Match List I with List II and select the correct answer using the code given below: List I | List II A. Dust flying off a beaten carpet | 1. Third Law of Motion B. Recoil of a gun | 2. Frictional force C. Catching a ball by pulling hands back | 3. Second Law of Motion (Impulse) D. Bicycle slowing down without pedalling | 4. First Law of Motion (Inertia)

Match List I with List II and select the correct answer using the code given below: List I | List II A. First Law of Motion | 1. Application in collision problems B. Second Law of Motion | 2. Measurement of Force ($F=ma$) C. Third Law of Motion | 3. Law of Inertia D. Conservation of Momentum | 4. Action and Reaction

With reference to Galileo’s experiments with the inclined plane, consider the following statements: 1. A marble rolling down an inclined plane decreases its velocity. 2. A marble climbing up an inclined plane decreases its velocity. 3. On an ideal frictionless horizontal plane, a marble would travel forever. Which of the statements given above are correct?

Which one of the following statements represents Newton's Third Law of Motion?

Which one of the following is a scalar quantity?

In the context of Newton's laws of motion, what is the primary function of a safety belt in a moving vehicle?

With reference to the relationship between mass and inertia, consider the following statements: 1. All bodies have the same inertia regardless of their size. 2. Heavier objects offer larger inertia than lighter objects. 3. The volume of an object is the sole quantitative measure of its inertia. Which of the statements given above is/are correct?

With reference to the property of inertia, which one of the following comparisons is correct?

The pain experienced in the hand after striking a wall is primarily due to: