Newtons First Law

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Sub Topics:
  • The Law of Inertia
  • Explanation on Newtons First Law
  • Examples of Newtons First Law

  • Newtons First Law states that "every body continues to be in its state of rest or of uniform motion in a straight line unless it is compelled to change that state by an external force impressed on it". The first part of the law deals with the state of rest of a body.

    Newtons First Law

    According to this, every body preserves its state of rest unless some external force compels it to change its state of rest. The following examples illustrate this part of the law.


    Examples of Newtons First Law

    In everyday life, a large number of examples upholding the law of inertia can be observed. Some of them are listed below:

    1. When a bus suddenly starts, the passengers sitting or standing in the bus tend to fall backward. This is due to inertia of rest and can be explained as follows: when the bus suddenly starts, the lower part of the body of the passenger which is in contact with the bus moves along with the bus while the upper part of the body tends to retain its state of rest due to inertia. As a result, the passenger falls backward.


      

    2. When a blanket is given a sudden jerk, the dust particles in it fail off due to inertia of rest.

    3. Consider a coin placed on the plate covering a tumbler. If the plate is sudden flicked off, the coin falls into the tumbler due to inertia of rest.

    4. When a branch of a tree is vigorously shaken the fruits and seeds in It fall down to inertia of rest.

    5. When moving bus suddenly stops, the passengers sitting or standing in the bus are thrown forward. This is due to inertia of motion and can be explained as follows: when the moving bus suddenly stops, the lower part of the body of the passenger contact with the bus suddenly comes to rest while the upper part of the body tends to retain its state of motion due to inertia. As a result, the passenger is thrown forward.

    6. A rider on a running horse is thrown forward when the horse stops suddenly due to inertia of motion.

    7. When a person jumps out of a moving vehicle, he falls forward due to inertia of motion.

    Explanation on Newtons First Law

    The marble in example
    1. Comes to rest because of the force of friction which oppose its motion. If the friction is completely eliminated then marble will preserve its state of uniform motion.
    2. In example 2, the body thrown vertically upwards gets retarded and momentarily comes to rest at a certain height above the ground due to force of gravity which opposes its motion. If gravity is eliminated then the body preserves its state of uniform motion. For example, a space ship far removed from all planets and other matter when given some velocity with the help of a propulsion system in it and the system turned off, will travel in space with the same velocity.

    Explanation on Newtons First Law

    The astronauts get a 'free ride'. Thus, to change the state of rest or of uniform motion of a body an external force must be impressed on the body. In other words, Newton's first law gives the definition of force. "Force is that external agency which changes or tends to change the state of rest or of uniform motion of a body in a straight line". Newton's first law of motion not only gives the definition of force but also reveals 'inertia' a fundamental property of all matter. As a result, Newton's first law of motion is also called the 'law of inertia'. 'Inertia is that property possessed by a material body by virtue of which the body preserves its state of rest or of uniform motion in a straight line'.

    Newtons First Law of Motion

    Newton's first law in everyday conditions:

    An object resting will remain at rest, permanently, so long as nothing pushes or even pulls onto it. An object within motion will remain in motion, driving a straight line, eternally, till something forces or even pulls onto it.

    Newtons First Law of Motion


    Examples of Newtons Second Law of Motion

    Newton's second law of motion relates to the behavior of objects that all existing forces usually are not balanced. The second law of motion states how the acceleration of the object depends upon two variables - the net force behaving upon the thing and also the mass with the object. The Velocity of the object will depend on directly upon the net force performing upon the object, as well as inversely upon the mass of the object. Since the force acting upon an item is elevated, the acceleration with the object is increased. As the mass of the object will be increased, the acceleration of the object is actually decreased.

    Examples of Newtons Third Law of Motion

    Newton's third law of motion informs us that whenever you push in opposition to something that pushes back for you having an equal and opposite force. Newtons 3rd law of motion will be the law of action as well as reaction. This tells exactly how forces interact with one another. The forces would be the action force and also the reaction force. You will have a reaction force Whether or not the object is non-living. Example:

    1. Whenever you push towards a wall the wall pushes you back.

    2. When the bat hits the ball the ball hits the bat.

    This air table offers a flat friction less surface area, consequently there might be no net horizontal force acting on the assembly.

    It may be observed from the diagram how the only force acting is vertical. Newton's first law informs us that the particle continues to be at rest as long as there's no unbalanced force performing on it, when placed on a body this is correct of the middle of mass. Considering that the gyroscope as well as the stand don't have any horizontal force acting on them there's no horizontal out of balance force, which means the middle of mass from the system should remain above the fixed level which it began at.

    1. A duster placed on a table continues to be at rest unless somebody displaces or lifts it by applying a force.
    2. A football lying on the ground continues to be in the same position unless somebody kicks it with a force.

    The second part of the law deals with the state of motion. According to this, everybody continues in its state of uniform motion in a straight line unless some external force compels it to change that state. This part of the law seems to be violated in our daily life. For example:
    1. A marble set rolling on the ground comes to rest after travelling a certain distance.
    2. A body thrown vertically upwards rises to a certain height and then falls down.

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