The Three Laws of Motion
The Three Laws of Motion was discovered by Newton,so these laws are also called Newton’s three laws of motion. The discovery of these laws of motion led Newton to be called as the father of mechanics a branch of physics. Newton first discovered the universal force of gravity which was succeeded by the discovery of three laws of motion. Three laws of motion are part of the physics book of middle and higher secondary school. Here each law of Newton is explained beautifully by an experienced physics teacher.
First Law of Motion:
The whole of the universe is controlled by certain balance forces on the basis of macroscopically and microscopically. All the objects in the universe are placed in their unique position,it is that’s we can say that universe is arranged in a matrix. All heavenly bodies are bounded by a certain balance gravitational force and all the particles in a matter are also bounded by the balance intermolecular and nuclear forces.The position of these objects in the universe can’t be changed until an external force is applied on them so Newton’s first law of motion is stated as follows.
An object remains in it’s own position until an external force is applied to it.
If a car is moving with a uniform speed,it will be carried at the same speed until an external force (i.e break or accelerator) is applied to it.
An obect remains in a stationary position until an external force is applied on it.
The first law of motion gave birth to the concept of inertia, the inertia is the physical property of all the objects. Inertia is the tendency of an object to resist a change in itself. It is proportional to the mass of an object.
Application of inertia: The head of the passenger is struck to the front sheat when the driver applies a sudden break.It happened because the sheat of the passenger is stuck the floor of the bus so as soon as the bus stops the sheat of the bus and lower part of the passenger’s body also stops but his upper part because of less mass (i.e inertia) still carried on to move resulting his head struck to front sheat.
When the trunk of a tree is shaken the leaves fall on the ground because the trunk regains its position faster due to high inertia but leaves still carried on in motion due to lesser inertia, therefore an imbalance outward force exerted on the leaves that detached the leaves from the surface of the tree and fall on the ground.
Second Law of Motion:
Newton discovered the second law of motion, as it is evident from the first law that if the mass of an object is more, its inertia will be more so the larger force is needed to displace a havier thing than the lighter thing. In displacing the heavier object to a particular point more time is required than displacing the lighter object to the same point. So another physical quantity momentum(P) was discovered by the newton, momentum is the product of mass and velocity. Newton observed that the force applied to an object while displacing it from one place to another is directly proportional to the rate of change of momentum.
Let the mass of an object is m, the initial object is u, the final velocity is v, and the time taken in achieving velocity v is t.
From the first equation of motion we have
Where a is the acceleration produced by the applied force
Substituting the value of a in above equation
F = kma
Where k is the constant of proportionality
Let m = 1kg, F= 1N and k = 1m/s²
k = 1 Ns²/kg
Putting this value in F = kma
F = ma
So, from this equation, we can also explain Newton’s second law of motion that if the same constant force is applied on two objects then the lighter object will be accelerated more compared to the heavier object.
Newton’s second law of motion states that acceleration is inversely proportional to the mass.
Third Law of Motion:
Newton obseved that every action has equal and opposite reaction that is known as Newton’s third law of motion.
Application of third law of motion: If we throw a ball by a certain force towards a wall then wall also strikes the ball by the same amount of force.
The great application of Newton’s third law of motion is the invention of rocket .In the rocket many type of chemicals are used ,under a high temperature and pressure cumbustion of these chemical produces hot gas ,these gasses ejects from the nozzle of the rocket with a very high velocity.The escaping of gases provides the rocket an equal amount of upward thrust that moves the rocket in forward direction towards the sky.
Verification of conservation of momentum with the help of Newton’s third law of motion:
Let object A of mass applied a force on object B of mass then object B will also apply an equal opposite force on object A.
Force is directly proportional to the rate of change of momentum.
Where and are the initial velocity of both objects and and are the final velocity of both the objects .
The initial momentum of both objects = Final momentum of both objects
Study science notes
The second law of motion
The universal law of gravitational force
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