Newton law of motion class 11

Newton's laws of motion give a scientific relationship between the forces that act on a body and the changes that occur due to this force. Sir Isaac Newton formulated the laws of motion in the year 1686 in his book ‘Principia Mathematica Philosophiae Naturalis’. What are the Three Laws of Motion? The Three Laws of Motion are: • Newton’s first law - Newton's first law of motion states that, if a body is in the state of rest or is moving with a constant speed in a straight line, then the body will remain in the state of rest or keep moving in the straight line, unless and until it is acted upon by an external force. • Newton’s second law - Newton's 2nd law of motion states that the rate of change of momentum of a body is directly proportional to the force applied on it, and the momentum occurs in the direction of the net applied force. • Newton’s third law - According to Newton's third law of motion, to every action, there is always an equal and opposite reaction. First Law of Motion This property of a body unable to change its state is called Inertia. Galileo Galilei first formulated the law of inertia for the horizontal motion of planet Earth. Later on, it was generalized to René Descartes. Before Galileo, it was believed that a force is required to keep a body moving. Galileo deduced that a body can't change its state unless acted by force (like friction). The state of motion or rest cannot be changed without applying force. If a body is moving in a particular direction, ...

Before Galileo and Newton, many people thought objects slowed down because they had a natural built in tendency to do so. But those people weren't taking into account the many forces—e.g., friction, gravity, and air resistance—here on Earth that cause objects to change their velocity. If we could observe the motion of an object in deep interstellar space, we would be able to observe the natural tendencies of an object's motion free from any external influences. In deep interstellar space, we would observe that if an object had a velocity, it would continue moving with that velocity until there was some force to cause a change in the motion. Similarly, if an object were at rest in interstellar space, it would remain at rest until there was a force to cause it to change its motion. Note the repeated use of the verb remains. We can think of this law as preserving the status quo of motion. Newton’s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity, either a change in magnitude or direction. An object sliding across a table or floor slows down due to the net force of friction acting on the object. But on an air hockey table, where air keeps the puck from touching the table, the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table. An external force is a force originating from outside an object rather than a force internal t...

• Home • Latest NEW • Class 11 Menu Toggle • Mechanics Menu Toggle • Physical Quantities • Vectors • Kinematics • Laws of Motion • Work, Energy and Power • Circular Motion • Gravitation • Equilibrium • Elasticity • Class 12 Menu Toggle • Electricity And Magnetism Menu Toggle • DC Circuit • Heating Effect of Current • EMF of a Cell • Electrical Circuit • Thermoelectric Effect • Magnetic Effect of Current • Alternating Current • Magnetic Properties of Materials • Electromagnetic Induction • Rotational Dynamics • Simple Harmonic Motion Force Force is defined as an external agent that can change or tries to change the state of rest or uniform motion of an object. It’s unit is Newton (N) in S.I. and Dyne in C.G.S. It is a vector quantity. 1N = 10 5 dyne Inertia The tendency of an object to remain in its own state of rest or uniform motion is called inertia. Types of inertia (i) Inertia of rest (ii) Inertia of motion (iii) Directional inertia Newton’s first law of motion Everybody in the universe continues in its own state of rest or uniform motion unless an external force acts upon it. i.e. for F external = 0, u = v Q. Newton’s first law of motion gives the definition of force and inertia. Justify. Solution: Newton’s first law of motion describes force in a qualitative way. According to the first law of motion, an object cannot change its state of rest or uniform motion without an external force. Thus, it can be concluded that force is an external agent that causes a body to ch...

More • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Newton’s Third Law of Motion You probably know that when you throw a ball against a wall, the ball exerts a force on the wall. Likewise, the wall puts force on the ball as a result of which the ball bounces off the wall. Similarly, earth pulls you down with gravitational force. What you may not realize is you are also exerting an equal amount of force on the earth. This remarkable fact is a consequence of Newton’s third law. Newton’s 3rd Law: If an object A exerts a force on object B, then object B must exert a force of equal magnitude and opposite direction back on object A. This law signifies a particular symmetry in nature: forces always occur in pairs, and one body cannot exert a force on another without experiencing a force itself. In the next few sections,...

Introduction When we look around us, we find the planets moving around the sun in orderly manner, movement of machinery parts in a factory, phases of the moon - all of them are following certain laws. They all are acted upon by certain forces. In the preceding two chapters, we described motion in terms of displacement, velocity and acceleration, i.e., we used kinematic quantities for describing motion without considering what might cause that motion. In order to understand this beauty, let us take a step forward by understanding " Force and laws of motion". Newton’s First Law of Motion According to this law, " A body continuous in its state of rest or constant velocity unless it is disturbed by external influence". In simple words, if no unbalanced external force acts on a body at rest, it will remain at rest and if it is moving with uniform motion, it will continue to do so. Or, if the resultant force on a body is zero, it remains unaccelerated. Inertia and mass Consider two bodies of unequal masses, say a table tennis ball and a cricket ball. If both balls are pushed with equal effort for same time, a cricket ball will have much smaller velocity as compared to the other ball. Cricket ball has resisted more than table tennis ball. Or, cricket ball has larger inertia than table tennis ball. So, we can generalise, a heavier body has larger inertia than a lighter body. Larger the mass, the larger is the inertia. So, mass is a measure of inertia. Recommended Books • • • • Rea...