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Chapter 2

Force and Pressure: Motion

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  • Force and Pressure: Motion
The following Topics and Sub-Topics are covered in this chapter and are available on MSVgo:

Introduction

You might have experienced pushing a car that sets it in motion. That is an example where we are applying force on the object. Force is an interaction between two things, while pressure is the force acting on a unit area in a perpendicular direction. Motion is the result of force and pressure on an object.

Now let us understand what motion is? Motion is a change in an object’s position with respect to time measured in a particular frame of reference. The frame of reference is a view that an individual might use to find out if the object is moving or not.

Let us consider a typical example of travelling on a train. It will seem to you that the trees are moving while you are stationary. It happens as the trees’ position changes concerning our reference frame, including the train. However, our position is not changing concerning the train movement. Hence, it seems that we are stationary.

There are various types of motion, namely,

  • Translatory motion
    Here in this type of motion, the particles of objects move simultaneously, covering an equal distance in the given time.When an object moves in a straight path, it is called rectilinear motion—for example, a car driving on the street.When an object moves in a bend or curved path, it is called curvilinear motion. For example, a ball falling on the ground.
  • Circular motion
    In a circular motion, an object moves along a circular path.
    For example, Moon revolving around the Earth in a circular orbit.
  • Oscillatory motion
    In this type of motion, the object repeats the action or movement several times.
    For example, a vibrating thread, the pendulum of a clock, etc.
  • Vibratory motion
    In this type of motion, the object changes its shape or size but does not move from its place. It is similar to oscillatory motion.

    For example, a plucked string in a sitar.
  • Periodic and Non-periodic motion
    When an object repeats the motion after regular intervals of time, it is called Periodic motion. When the object repeats its motion at an irregular time interval, it is called Non-periodic motion.
    An example of period motion is Earth revolving around the Sun.
    An example of non-periodic motion is tides produced in the sea.
  • Multiple motions
    In this motion type, an object is performing more than one simple movement.For example, You are travelling in a car. The wristwatch that you are wearing is performing linear motion as the vehicle is moving. Also, it is performing circular motion as the second hand is moving.
  • Random motion
    In this type of motion, it is difficult to predict the direction of movement.
    For example, a Flying butterfly, fish moving in the sea.

When a body covers an equal distance in equal time intervals, it is called Uniform motion. In this case, the speed is constant.

When an object covers an unequal distance in equal time intervals, it is called Non-uniform motion. In this case, the speed will vary with time.

Examples of Uniform and Non-uniform motion are trains moving at a constant speed and cars driving on high traffic roads.

Mass is the amount of matter present in an object. It is denoted using “m” or “M.” Its standard unit is kg or gm.

Weight is the quantity of gravitational force that is acting on an object of mass m. It is denoted using “W.”

W=m g , where g is the acceleration due to gravity.

Its standard unit is Newton(N).

Let us talk about the difference between mass and weight.

 

MassWeight
It is a property of matter.Weight is proportional to acceleration due to gravity.
It remains constant irrespective of the location.Weight of the body changes with a change in acceleration due to gravity.
It is a scalar quantity and is defined using magnitude alone.It is a vector quantity and defined using magnitude and direction.
Mass is never zero.Weight can be zero(like in space where gravity is zero)
It is measured using a beam balance.It is measured using a spring balance.

Force and Pressure can bring about a movement in the object. Mass and weight are different due to the acceleration due to gravity acting on every object. The weight of a body is zero in space(as g=0).

  1. What is the effect of force and pressure on any object?
    When force and pressure are applied to any object, then either it changes its shape or size. It can also result in the movement of the object.
  2. Define motion.
    Motion is a change in an object’s position concerning time, like riding a bike, a clock ticking 1’0 clock, etc.
  3. Is the weight of an object on the Moon the same as that on the Earth?
    No, it is different as acceleration due to gravity is different on Moon and Earth.
  4. What are the various types of translatory motion?
    The different types of translatory motion are Rectilinear and Curvilinear motion.
  5. Give examples for uniform and non-uniform motion?
    An example of uniform motion is a pendulum of the clock. An example of non-uniform motion is cycling on a bumpy road.
  6. Differentiate between Force and Pressure.
    ForcePressure
    Force is pushing or pulling a given object.The pressure is the force applied to a unit area of an object.
    It is measured using Dynometer.It is measured using Manometer.
    It is defined using magnitude and direction.It is defined using the magnitude alone.
    Its S.I unit of measurement is Newton(N).Its S.I unit of measurement is Pascal(P).

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