<–2/”>a >Motion
Motion is a change in position of an object with respect to time. Motion is typically described in terms of displacement, distance, velocity, acceleration, time and speed.
The branch of physics which deals with the study of motion of material objects is called mechanics.
Mechanics is divided into following branches.
(i) Statics : Statics is the branch of mechanics which deals with the study of motion of objects under the effect of forces in equilibrium.
(ii) Kinematics :
It is that branch of mechanics which deals with the study of motion of object without taking into account the factors (i.e. nature of forces, nature of bodies etc.) which cause motion. Here time factor plays an essential role.
(iii) Dynamics :
It is that branch of mechanics which deals with the study of motion of objects taking into account the factors whichcause motion.
Rest : An object is said to be at rest if it does not change its position with time, with respect to its surroudings.
A book lying on a table, a person sitting in a chair are the examples of rest.
Motion : An object is said to be in motion if it changes its position with time, with respect to its surroundings.
Example : A bird flying in air, a train moving on rails, a ship sailing on water, a man walking on road are some of the examples of motion, visible to the eye. Motion of gas Molecules is an example of motion, invisible to the eye.
Rest & Motion are relative terms :
When we say that an object is at rest or in motion,then this statement is incomplete and meaningless. Basically, rest & motion are relative terms. An object which is at rest can also be in motion simultaneously. This can be illustrated as follows.
The passengers sitting in a moving bus are at rest with respect to each other but they are also in motion at the same time with respect to the objects like trees, buildings on the road side. So the motion and rest are relative terms.
Rectilinear motion :
If a particle moves in a fixed direction, the motion of this type is called rectilinear motion or one dimensional motion.For example the motion of an ant on a wire is a rectilinear motion.
Two dimensional motion :
If the motion of a particle is in such a way that its position remains on a fixed plane, then the motion of a particle is called two dimensional motion.
Laws Of Motion
First Law of Motion
A body continue to be in its state of rest or of uniform motion along a straight line, unless it is acted upon by some external force to change the state
(1) If no net force acts on a body, then the velocity of the body cannot change i.e. the body cannot accelerate.
(2) Newton‟s first law defines inertia and is rightly called the law of inertia. Inertia are of three types :Inertia of rest, Inertia of motion, Inertia of direction
(3) Inertia of rest : It is the inability of a body to change by itself, its state of rest. This means a body atrest remains at rest and cannot start moving by its own.
Second Law of Motion
(1) The rate of change of linear momentum of a body is directly proportional to the external force appliedon the body and this change takes place always in the direction of the applied force.
(2) If a body of mass m, moves with velocity v then its linear momentum can be given by p= mv and if force is applied on a body, then Force = mass ? acceleration
Third Law of Motion
To every action, there is always an equal (in magnitude) and opposite (in direction) reaction.
(1) When a body exerts a force on any other body, the second body also exerts an equal and opposite forceon the first.
(2) Forces in nature always occurs in pairs. A single isolated force is not possible.
(3) Any agent, applying a force also experiences a force of equal magnitude but in opposite direction. Theforce applied by the agent is called „Action‟ and the counter force experienced by it is called „Reaction‟.
(4) Action and reaction never act on the same body. If it were so the total force on a body would have always been zero i.e. the body will always remain in equilibrium.
(5) If F (AB)= force exerted on body A by body B (Action) and F(BA)= force exerted on body B by body A (Reaction) Then according to Newton‟s third law of motion F (AB) = F(BA)
(6) Example : (i) A book lying on a table exerts a force on the table which is equal to the weight of the book. This is the force of action.,
Force is any interaction that, when unopposed, will change the motion of an object. A force can cause an object with mass to change its velocity (which includes to begin moving from a state of rest), i.e., to accelerate. Force can also be described intuitively as a push or a pull. A force has both magnitude and direction, making it a vector quantity.
Newton’s first law of motion states that an object either remains at rest or continues to move at a constant velocity, unless it is acted upon by an external force. This is also 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 the object, and inversely proportional to the mass of the object. This is also known as the law of acceleration.
Newton’s third law of motion states that for every action, there is an equal and opposite reaction. This is also known as the law of action and reaction.
Friction is a force that opposes the relative motion of two objects or materials. It is caused by the interaction of the microscopic surface features of the two materials. Friction can be reduced by using lubricants, which reduce the interaction between the surface features.
Air resistance is a force that opposes the motion of an object through the air. It is caused by the interaction of the object with the air molecules. Air resistance can be reduced by streamlining the object, which reduces the surface area that is exposed to the air.
Drag is a type of air resistance that acts in the direction opposite to the motion of the object. It is caused by the interaction of the object with the air molecules. Drag can be reduced by streamlining the object, which reduces the surface area that is exposed to the air.
Terminal velocity is the maximum speed that an object can fall through a fluid. It is reached when the force of gravity is equal to the force of air resistance.
Centripetal force is a force that acts towards the center of a circular path. It is required to keep an object moving in a circular path. Centripetal force can be provided by gravity, tension, or a combination of both.
Centrifugal force is an apparent force that acts outwards from the center of a circular path. It is not a real force, but rather an illusion caused by the inertia of the object.
Torque is a force that causes rotation. It is defined as the product of the force and the distance from the point of rotation. Torque can be used to change the angular velocity of an object, or to cause it to rotate.
Angular momentum is the rotational equivalent of linear momentum. It is defined as the product of the mass of an object, the radius of its rotation, and its angular velocity. Angular momentum is conserved, which means that it cannot be created or destroyed.
Rotational inertia is the resistance of an object to changes in its rotation. It is defined as the product of the mass of an object and the square of its radius of rotation. Rotational inertia is important in determining the torque required to rotate an object.
Work is the transfer of energy from one object to another by means of a force. It is defined as the product of the force and the distance over which the force is applied. Work can be used to change the kinetic energy of an object, or to do work on another object.
Power is the rate at which work is done. It is defined as the work done divided by the time taken to do the work. Power is important in determining the rate at which an object can accelerate.
Energy is the ability to do work. It can exist in many forms, including kinetic energy, potential energy, and heat energy. Energy can be converted from one form to another, but it cannot be created or destroyed.
Kinetic energy is the energy of motion. It is equal to one half the mass of an object times the square of its velocity. Kinetic energy is important in determining the speed of an object.
Potential energy is the energy stored in an object due to its position or state. It can be converted into kinetic energy, but it cannot be created or destroyed. Potential energy exists in many forms, including gravitational potential energy, elastic potential energy, and chemical potential energy.
Gravitational potential energy is the energy stored in an object due to its position in a gravitational field. It is equal to the mass of the object times the acceleration due to gravity times the height of the object. Gravitational potential energy is important in determining the motion of objects in a gravitational field.
Mechanical energy is the sum of the kinetic energy and potential energy of an object. It is conserved, which means that it cannot be created or destroyed. Mechanical energy can be converted from one form to another, but the total amount of mechanical energy remains constant.
Conservation of energy is the principle that energy can neither be created nor destroyed,
What is a force?
A force is an interaction that, when unopposed, will change the motion of an object. A force can cause an object with mass to change its velocity (which includes to begin moving from a state of rest), i.e., to accelerate. Force can also be described intuitively as a push or a pull. A force has both magnitude and direction, making it a vector quantity.
What are the three laws of motion?
The three laws of motion are the laws that, together, laid the foundation for classical mechanics. They describe the relationship between a body and the forces acting upon it, and its motion in response to those forces.
The first law of motion is the law of inertia. It states that, if an object is at rest, it will remain at rest, and if it is in motion, it will remain in motion with the same speed and in the same direction, unless acted upon by an unbalanced force.
The second law of motion is the law of acceleration. It states that the acceleration of an object is directly proportional to the net force acting on the object, and inversely proportional to the mass of the object.
The third law of motion is the law of action and reaction. It states that for every action, there is an equal and opposite reaction.
What is inertia?
Inertia is the resistance of any physical object to any change in its motion. This includes changes to the object’s speed, direction, or state of rest.
What is mass?
Mass is a property of a physical body that determines the strength of its mutual gravitational attraction to other bodies. It is also the measure of an object’s resistance to acceleration when a net force is applied.
What is weight?
Weight is the force of gravity on an object. It is calculated by multiplying the mass of the object by the acceleration due to gravity.
What is acceleration?
Acceleration is the rate at which velocity changes. It is calculated by dividing the change in velocity by the time it takes for the change to occur.
What is velocity?
Velocity is the rate at which an object changes its position. It is calculated by dividing the change in position by the time it takes for the change to occur.
What is momentum?
Momentum is the product of an object’s mass and velocity. It is a vector quantity, meaning that it has both magnitude and direction.
What is energy?
Energy is the ability to do work. It can be stored in many different forms, including kinetic energy, potential energy, and thermal energy.
What is work?
Work is the transfer of energy from one object to another by means of a force. It is calculated by multiplying the force applied by the distance over which the force is applied.
What is power?
Power is the rate at which work is done. It is calculated by dividing the work done by the time it takes to do the work.
What is torque?
Torque is the rotational equivalent of force. It is calculated by multiplying the force applied by the distance from the point of application of the force to the axis of rotation.
What is angular momentum?
Angular momentum is the rotational equivalent of momentum. It is calculated by multiplying the mass of an object by its radius of rotation and its angular velocity.
What is a system?
A system is a group of objects that interact with each other. The state of a system is determined by the values of its properties, such as temperature, pressure, and volume.
What is a closed system?
A closed system is a system that does not exchange matter with its surroundings.
What is an open system?
An open system is a system that exchanges matter with its surroundings.
What is a thermodynamic system?
A thermodynamic system is a system that is studied in Thermodynamics. Thermodynamics is the study of heat and its relation to other forms of energy and work.
What is a thermodynamic process?
A thermodynamic process is a change in the state of a thermodynamic system.
What is a reversible process?
A reversible process is a thermodynamic process that can be reversed without leaving any trace on the system or its surroundings.
What is an irreversible process?
An irreversible process is a thermodynamic process that cannot be reversed without leaving some trace on the system or its surroundings.
What is entropy?
Entropy is a measure of the disorder of a system. It is a state function, meaning that its value depends only on the state of the system and not on how the system reached that state.
**What is the second law
What is the SI unit of force?
(A) Newton (N)
(B) Kilogram (kg)
(C) Meter (m)
(D) Second (s)What is the first law of motion?
(A) 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.
(B) The acceleration of an object is directly proportional to the net force acting on the object, and inversely proportional to the mass of the object.
(C) For every action, there is an equal and opposite reaction.What is the second law of motion?
(A) 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.
(B) The acceleration of an object is directly proportional to the net force acting on the object, and inversely proportional to the mass of the object.
(C) For every action, there is an equal and opposite reaction.What is the third law of motion?
(A) 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.
(B) The acceleration of an object is directly proportional to the net force acting on the object, and inversely proportional to the mass of the object.
(C) For every action, there is an equal and opposite reaction.What is the difference between mass and weight?
(A) Mass is a measure of how much matter is in an object, while weight is a measure of the force of gravity on an object.
(B) Mass is a scalar quantity, while weight is a vector quantity.
(C) Mass is constant, while weight can vary depending on the gravitational field.What is inertia?
(A) Inertia is the tendency of an object to resist changes in its motion.
(B) Inertia is the measure of how much matter is in an object.
(C) Inertia is the force of gravity on an object.What is momentum?
(A) Momentum is the product of an object’s mass and velocity.
(B) Momentum is the measure of how much matter is in an object.
(C) Momentum is the force of gravity on an object.What is kinetic energy?
(A) Kinetic energy is the energy of motion.
(B) Kinetic energy is the energy of an object due to its position.
(C) Kinetic energy is the energy of an object due to its temperature.What is potential energy?
(A) Potential energy is the energy of an object due to its position.
(B) Potential energy is the energy of motion.
(C) Potential energy is the energy of an object due to its temperature.What is the difference between elastic and inelastic collisions?
(A) In an elastic collision, the total kinetic energy of the system is conserved, while in an inelastic collision, the total kinetic energy of the system is not conserved.
(B) In an elastic collision, the total momentum of the system is conserved, while in an inelastic collision, the total momentum of the system is not conserved.
(C) In an elastic collision, the total energy of the system is conserved, while in an inelastic collision, the total energy of the system is not conserved.