What are the three laws of motion?

The three laws of motion were introduced by S. Isaac Newton hence they are also called Newton’s laws of motion. Newton’s first law of motion says that a moving body will continue to move and a body at rest will always remain at rest as long as they are not affected by any amount of external force. Newton’s second law of motion says that the change in momentum of a body with respect to time is always equal to the applied force on a body. Newton’s third law of motion says that for every action force acting on a body in a given direction there exists a reaction force acting on the same body with the same amount of force but opposite in direction.

What is Newton's Second Law of motion formula?

Newton’s Second law of motion gives the relationship between three physical quantities of a body namely Force acting on a body force vector, the acceleration produced in a body acceleration vector, and mass of the body, and these quantities are related as F=ma This relation is known as Newton's second law of motion formula. and Newton's second law of motion is also called Balance of Linear momentum.

Write some Newton's Law of motion examples.

Few most common examples of newton’s laws of motion are: Opening and closing a door by pushing or pulling it by mechanical force which changes the direction of the door is an example of Newton's first law of motion as well as Newton's second law of motion. Hitting a football by a player changes the direction and velocity of football is an example of Newton's second law of motion. A laptop resting on a table exerting a force of its weight on the table in a downward direction as an active force and a table exerting the same amount of reaction force on a laptop in the upward direction is an example of Newton's third law of motion.

What is Newton’s First Law of Motion?

Newton’s first law of motion is based upon the concept of inertia, and it states that anybody as long as unaffected by any external force will keep the same inertia such that a body having inertia of rest will keep at rest and a body having inertia of motion will keep moving. And Newton’s first law of motion is sometimes also called the Law of Inertia.

According to Newton’s second law of motion, What is the force acting on a body having a mass of 2kg moving with an acceleration of 6ms-2?

From, Newton’s second law of motion we know that force acting on a body is defined as the product of the mass of the body and acceleration acting on the body which is written as F=ma here we have given that, m=2kg and a=a=6ms -2 so on putting the values, the force can be calculated as F=2×6=12Kgms -2 . Hence, the force acting on the body is 12Newton.

How does mass affect an object's acceleration according to Newton's Second Law?

According to Newton's Second Law, mass and acceleration are inversely related. This means that for a given force, objects with greater mass will experience less acceleration, while objects with less mass will experience greater acceleration. Doubling the mass of an object will halve its acceleration for the same applied force.

Why do heavier objects fall at the same rate as lighter objects in a vacuum?

In a vacuum, all objects fall at the same rate regardless of their mass due to the relationship between mass and gravitational force. While a heavier object experiences a greater gravitational force, it also has more mass to accelerate. These effects cancel out, resulting in the same acceleration for all objects in free fall, as described by Newton's Second Law.

How do Newton's Laws of Motion explain the motion of a car during a collision?

During a collision, all three of Newton's Laws come into play. The First Law explains why passengers continue moving forward when the car suddenly stops (inertia). The Second Law describes how the force of impact affects the car's acceleration. The Third Law accounts for the equal and opposite forces exchanged between the colliding objects.

What is the difference between mass and weight?

Mass is a measure of the amount of matter in an object and remains constant regardless of location. Weight, on the other hand, is the force exerted on an object due to gravity and can change depending on the strength of the gravitational field. Weight is calculated using Newton's Second Law: W = mg, where m is mass and g is the acceleration due to gravity.

What is Newton's First Law of Motion?

Newton's First Law of Motion states that an object at rest stays at rest, and an object in motion stays in motion with the same speed and in the same direction, unless acted upon by an unbalanced force. This law describes the concept of inertia, which is the tendency of objects to resist changes in their state of motion.

How does inertia relate to Newton's First Law?

Inertia is directly related to Newton's First Law. It is the property of matter that causes objects to resist changes in their state of motion. Inertia explains why objects at rest tend to stay at rest, and objects in motion tend to stay in motion, unless acted upon by an external force.

Why doesn't a book slide off a table when a tablecloth is quickly pulled out from under it?

This phenomenon is an example of Newton's First Law in action. The book has inertia and tends to remain at rest. When the tablecloth is pulled quickly, the force applied is not enough to overcome the book's inertia in the short time of contact. As a result, the book remains in place while the tablecloth moves out from under it.

How do Newton's Laws apply to objects in circular motion?

In circular motion, Newton's Laws still apply, but with some nuances. The First Law explains why objects want to move in a straight line (tangent to the circle) when released. The Second Law relates the centripetal force to the object's mass and acceleration. The Third Law accounts for the equal and opposite forces between the object and whatever is providing the centripetal force (e.g., tension in a string or friction on a curved track).

How do Newton's Laws explain the motion of a person walking?

When a person walks, they push backward against the ground (action). According to Newton's Third Law, the ground pushes back with an equal and opposite force (reaction). This reaction force propels the person forward. The First Law explains why it takes effort to start walking (overcoming inertia), and the Second Law describes how the force applied affects the person's acceleration.

What is Newton's Third Law of Motion?

Newton's Third Law of Motion states that for every action, there is an equal and opposite reaction. This means that when one object exerts a force on another object, the second object exerts an equal force back on the first object, but in the opposite direction.

How does Newton's Third Law explain rocket propulsion?

Rocket propulsion is a perfect example of Newton's Third Law in action. As the rocket expels hot gases downward (action), the gases exert an equal and opposite force on the rocket, pushing it upward (reaction). This reaction force is what propels the rocket into space.

Why don't action-reaction pairs cancel each other out?

Action-reaction pairs don't cancel each other out because they act on different objects. While the forces are equal in magnitude and opposite in direction, they are applied to separate bodies. For example, when you push against a wall, the wall pushes back with an equal force, but these forces act on you and the wall respectively, not on the same object.

What is meant by "net force" in Newton's Second Law?

Net force refers to the vector sum of all forces acting on an object. It takes into account both the magnitude and direction of each force. When calculating acceleration using F = ma, it's crucial to use the net force rather than individual forces. If the net force is zero, the object's velocity remains constant (it may be at rest or moving with constant velocity).

Why do you feel pushed back into your seat when a car accelerates forward?

This sensation is due to inertia, as described by Newton's First Law. When the car accelerates forward, your body tends to remain at rest relative to the Earth. This creates the feeling of being pushed back into the seat, although it's actually the seat pushing you forward to match the car's acceleration. The force you feel is the seat overcoming your inertia.

How does air resistance affect the application of Newton's Laws?

Air resistance is a force that opposes the motion of objects through air. It affects the application of Newton's Laws by introducing an additional force that must be considered when analyzing motion. For falling objects, air resistance eventually balances the gravitational force, leading to a terminal velocity where acceleration becomes zero, as per the Second Law.

What is the relationship between force and acceleration for a constant mass?

For a constant mass, force and acceleration are directly proportional, as described by Newton's Second Law (F = ma). This means that doubling the force will double the acceleration, tripling the force will triple the acceleration, and so on. This relationship is linear, assuming the mass remains constant.

How do Newton's Laws explain the concept of equilibrium?

Equilibrium in physics refers to a state where the net force acting on an object is zero. According to Newton's First Law, an object in equilibrium will remain at rest if it's stationary, or continue moving with constant velocity if it's already in motion. The Second Law (F = ma) shows that when the net force is zero, acceleration is also zero, maintaining the equilibrium state.

Why is it easier to push a shopping cart on a smooth floor than on a rough one?

This difference is due to friction, which relates to Newton's Laws. On a smooth floor, there's less friction opposing the motion of the cart. According to Newton's Second Law, with less opposing force, less effort (force) is required to achieve the same acceleration. The Third Law is also relevant, as the friction force is a reaction to the cart's motion along the floor.

How do seat belts work in relation to Newton's Laws?

Seat belts work based on Newton's First Law of Motion. In a collision, a passenger's body tends to continue moving at the same speed and direction as before the crash (inertia). The seat belt provides a force to slow down the passenger's body along with the car, preventing them from continuing to move forward and potentially colliding with the car's interior.

What is the significance of Newton's Laws in everyday life?

Newton's Laws are fundamental to understanding motion and forces in everyday life. They explain phenomena like why we need seat belts, how cars accelerate and brake, why it's harder to push heavy objects, and how we walk. These laws form the basis for designing everything from transportation systems to sports equipment, and understanding them helps us interact more effectively with our physical environment.

How do Newton's Laws apply to objects floating in space?

In space, Newton's Laws still apply, but their effects are more noticeable due to the absence of significant external forces like friction and air resistance. The First Law is particularly evident: objects in motion tend to stay in motion indefinitely. The Second Law explains why small forces can produce significant accelerations in the vacuum of space. The Third Law is crucial for spacecraft propulsion, as discussed in the rocket example.

What is the role of friction in Newton's Laws?

Friction plays a significant role in the application of Newton's Laws. It's often the force that opposes motion, as described in the First Law. In the Second Law, friction affects the net force and thus the acceleration of objects. The Third Law explains the nature of friction as a reaction force between surfaces. Understanding friction is crucial for accurately predicting and explaining the motion of objects in real-world scenarios.

How do Newton's Laws explain the motion of a pendulum?

A pendulum's motion can be explained using all three of Newton's Laws. The First Law accounts for the pendulum's tendency to continue swinging. The Second Law describes how gravity and tension in the string affect the pendulum's acceleration at different points in its swing. The Third Law explains the equal and opposite forces between the pendulum and its support, and between the pendulum and the air it moves through.

Why does a heavier person sink deeper into a soft chair than a lighter person?

This phenomenon is related to Newton's Second and Third Laws. According to the Second Law, the force exerted by a person on the chair is proportional to their mass (F = mg, where g is gravity). The Third Law states that the chair exerts an equal and opposite force back on the person. To balance these forces, a heavier person will sink deeper, compressing the chair's material more to generate the required upward force.

How do Newton's Laws explain the concept of momentum?

Momentum is closely related to Newton's Laws, particularly the Second Law. Momentum is defined as the product of mass and velocity (p = mv). The Second Law can be rewritten in terms of momentum: F = dp/dt, where F is the net force and dp/dt is the rate of change of momentum. This form of the Second Law shows that a force causes a change in momentum over time, which is fundamental to understanding collisions and impulse.

What is the difference between static and kinetic friction, and how do they relate to Newton's Laws?

Static friction is the force that prevents an object from starting to move, while kinetic friction opposes the motion of objects already in motion. Both types of friction are reaction forces (Third Law) that affect the net force on an object (Second Law). Static friction can vary up to a maximum value, while kinetic friction is generally constant and lower than the maximum static friction. Understanding these forces is crucial for accurately predicting when objects will start moving and how they'll continue to move.

How do Newton's Laws explain the motion of a car going around a curve?

When a car goes around a curve, all three of Newton's Laws are at work. The First Law explains why the car wants to continue in a straight line (inertia). The Second Law relates the centripetal force needed to keep the car on the curved path to its mass and velocity. The Third Law accounts for the equal and opposite forces between the car's tires and the road, which provide the necessary friction for turning.

Why does a karate expert break a board with a quick, sharp blow rather than a slow push?

This technique is based on Newton's Second Law. The force needed to break the board depends on the acceleration of the hand at impact, not just the force applied. A quick, sharp blow produces a very high acceleration over a short time, resulting in a large force (F = ma). A slow push, even with the same ultimate force, spreads the acceleration over a longer time, reducing its effectiveness in breaking the board.

How do Newton's Laws explain the concept of apparent weight in an elevator?

Apparent weight changes in an elevator due to acceleration, as explained by Newton's Second Law. When the elevator accelerates upward, you feel heavier because the floor must push up on you with extra force to accelerate you upward. When it accelerates downward, you feel lighter because the floor pushes up with less force. The Third Law explains the equal and opposite forces between you and the elevator floor.

Laws of Motion - First, Second, Third Law of Motion

Physics
Laws of Motion
Laws of Motion

Laws of Motion - First, Second, Third Law of Motion

Q: What is Newton's Second Law of Motion?

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, it is expressed as F = ma, where F is the net force, m is the mass of the object, and a is its acceleration.

Vishal kumarUpdated on 02 Jul 2025, 04:42 PM IST

The motion principles described by Sir Isaac Newton lay the groundwork of classical mechanics and describe how objects are moved and how they interact. These laws- the first, second, and third, control things such as the motion of the planet or the working of simple machines. It is possible to observe them for instance in riding a car, throwing a ball, or even in walking, they are thus very essential in understanding and predicting motion.

This Story also Contains

What is the Newton’s 1st Law of Motion?
What is Newton's Second Law of Motion?
Newton’s 3rd Law of Motion

Laws of Motion

What is the Newton’s 1st Law of Motion?

According to Newton's first law of motion, a moving body will keep moving as long as it’s not acted by any external force and a body at rest will keep being at rest unless acted by some amount of external force. This tendency of a body to remain moving or remain at rest is known as Inertia. This is Newton's first law of motion. It is also called the law of inertia.

Newtons first law of motion

The concept of Inertia was first discovered by scientist Galileo Galilei and the ability of a body to keep itself at rest is called Inertia of rest whereas The tendency of the body to keep moving is called Inertia of motion.

Examples of Newton’s First Law of Motion

The most common examples of Newton’s first law of motion are listed as:

When car brakes are applied suddenly, we feel a force towards the front of the car. This is because of Newton's first law of motion as a car and we were moving and when the car came to rest after applying brakes we kept moving forward due to inertia of motion.
When we move a cloth consisting of dust with some force we see that dust particles from the cloth come out, this is also due to the first law of motion as dust particle and cloth both were at rest but suddenly cloth came at motion due to applied force and dust particles remain in their position due to inertia of rest. It's also an example of Newton's first law of motion.
The motion of heavenly planets is due to the inertia of motion because once they are set in motion there is no external force applying to them so they are moving at their constant speed is also an example of Newton’s first law of motion.

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What is Newton's Second Law of Motion?

According to Newton's second law of motion, if any amount of force is applied on a body externally then this force will always be equal to the change that takes place in the momentum of a body.

Momentum is defined as the product of the mass and velocity of a body and mathematically written as $p=m v$ where p is the momentum vector and v is the velocity vector.

Newtons second law of motion

Now, from the definition of Newton’s second law of motion, we know that if force F vector is applied on the body and change in momentum is written as m dv/dt and this quantity will be equal to force written as F=mdvdt and we know that rate of change in velocity is equal to acceleration produced in the body so we can write Force applied on the body as F=ma Hence, Newton’s second law of motion is simply written as $\mathrm{F}=\mathrm{ma}$. This is known as Newton's second law of motion formula.

Examples of Newton’s Second Law of Motion:

Some of the most common examples of Newton’s second law of motion are listed:

When a cricketer hits a ball, the ball changes its direction and velocity, this is because of Newton’s second law of motion as the bat hits the ball with some force and force is equal to the change in momentum of the ball hence, the ball gets direction in the direction of force applied by the bat.
When we apply some force by pushing or pulling on objects like tables at rest, the objects get displaced from their position in the direction of the applied force, this is also due to Newton's second law of motion as the force applied on the objects changes the magnitude and direction of acceleration produced in the body.
When a moving charge particle enters in the presence of a magnetic field it experiences magnetic force and hence due to this force, the charged particle changes its direction of motion and also has a change in its momentum which is only due to Newton's second law of motion.

Newton’s 3rd Law of Motion

According to Newton’s third law of motion, if we first body applies some force to the second body then the second body will also exert the same amount of force on the first body but in the opposite direction or we can say when there is an action force by a body there will also be a reaction force which will have a direction opposite to that of action force.

Newtons third law of motion

Examples of Newton’s Third Law of Motion

Some of the most common examples of Newton’s third law of motion are listed as:

When objects are placed over other objects such as a notebook placed on a table or a human standing on the ground then the action force is the force acted by the notebook on the table in a downward direction and the force acted by the human body on the ground is the force of gravity and its equal to the reaction force acted by table on the notebook and by the ground on the human body but in the opposite direction which is upwards. and it's due to Newton’s third law of motion.
When we apply some force on a wall, the wall also exerts the same amount of force but opposite in direction is also an example of Newton's third law of motion.

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Frequently Asked Questions (FAQs)

Q: How do Newton's Laws explain the concept of weightlessness in orbit?

Weightlessness in orbit is a consequence of Newton's Laws, particularly the First and Second Laws. Objects in orbit

Q: What is the significance of Newton's Laws in the design of safety features in vehicles?

Newton's Laws are fundamental in designing vehicle safety features. The First Law explains why passengers continue moving forward during a sudden stop, necessitating seat belts and airbags. The Second Law helps engineers calculate the forces involved in collisions and design crumple zones to extend the time of impact, reducing acceleration and thus the force experienced by passengers. The Third Law is considered in designing how vehicles interact with each other and with barriers during collisions.

Q: How do Newton's Laws explain why it's harder to stop a moving truck than a moving bicycle?

This difference is primarily due to Newton's Second Law and the concept of momentum. A truck has much more mass than a bicycle, so at the same velocity, it has much more momentum (p = mv). To stop an object, you need to apply an impulse equal to its momentum. The Second Law (F = ma) shows that for the same acceleration (to stop in the same distance), a larger mass requires a larger force. Therefore, it takes more force over a longer time (larger impulse) to stop the truck.

Q: What is the relationship between Newton's Laws and the concept of impulse?

Impulse is closely related to Newton's Second Law. Impulse is defined as the product of force and the time over which it acts, and it equals the change in momentum of an object. This relationship is derived from the Second Law: F = ma can be rewritten as F = m(Δv/Δt), where Δv is the change in velocity. Multiplying both sides by Δt gives FΔt = mΔv, which is the impulse-momentum theorem. This concept is crucial in understanding collisions and impacts.

Q: How do Newton's Laws explain the motion of a yo-yo?

A yo-yo's motion involves all three of Newton's Laws. The First Law explains why the yo-yo continues spinning once set in motion. The Second Law describes how the force of gravity and the tension in the string affect the yo-yo's acceleration as it moves up and down. The Third Law accounts for the equal and opposite forces between the yo-yo and the string, and between the yo-yo and the air it moves through.

Q: What is the significance of Newton's Laws in sports?

Newton's Laws are crucial in understanding and improving sports performance. The First Law explains why it's hard to start or stop quickly. The Second Law is key in activities involving acceleration, like sprinting or throwing. The Third Law is evident in actions like jumping (pushing against the ground) or hitting a ball (equal and opposite forces between bat and ball). Understanding these laws helps athletes and coaches optimize techniques and equipment design.

Q: How do Newton's Laws explain the concept of centrifugal force?

Centrifugal force is not a real force, but rather an apparent force felt in a rotating reference frame. It's a consequence of Newton's First Law: objects want to move in a straight line, but in circular motion, they're constantly being pulled toward the center. This inward pull (centripetal force) is real and follows Newton's Second Law. The outward "centrifugal force" felt by passengers is actually their inertia resisting the change in direction, as described by the First Law.

Q: Why does a person in a car moving at constant velocity feel stationary?

This perception is due to Newton's First Law. Inside the car, everything (including the person) is moving at the same constant velocity as the car. There's no acceleration relative to the car's interior, so no net force is felt. The person and objects inside the car are in an inertial reference frame, where the First Law holds true. Only by looking outside or experiencing a change in the car's motion would the person perceive their actual velocity relative to the Earth.

Q: How do Newton's Laws apply to fluids and gases?

Newton's Laws apply to fluids and gases, but their application can be more complex due to the nature of these substances. In fluids, forces are distributed over surfaces (pressure), but still follow the principles of the Laws of Motion. For example, the buoyant force in fluids is a result of the Third Law, where the upward force on an object is equal to the weight of the fluid displaced. The motion of fluid particles and the concepts of fluid dynamics are all based on Newton's Laws.

Q: What is the relationship between Newton's Laws and the concept of work?

Work in physics is defined as force multiplied by displacement in the direction of the force. This concept is closely tied to Newton's Second Law. When a force causes an object to accelerate (Second Law), it typically does work on the object, changing its kinetic energy. The relationship between force, displacement, and work helps explain energy transfer and conservation in mechanical systems.

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