# Motion

Motion

Introduction

Everything in the universe moves. We live in a universe that is in continual motion. The fundamental particle of matter, that is, the atom, is in constant motion too. Every physical process in the universe is composed of motion of some sort.

Reference frame:A frame in which an observer is situated and makes his observations is known as his/her 'frame of reference.

Example of Frames of Reference

Suppose a train is moving and a person is sitting inside the train watching a tree pass by. In this case, the train is the frame of reference and the tree appears to be moving. If we consider the opposite of it, a person on the platform will look at the tree as a stationary object.

Definition:-Motion of a body can be referred to as its change in position depending on its surroundings in a given time interval.

Motion can defined in term of:-

• Distance
• Displacement
• Speed
• Time
• Velocity
• Acceleration

Distance:

Distance is the total movement of an object without any regard to direction. We can define distance as to how much ground an object has covered despite its starting or ending point.

Example:

A vehicle travels east for 5 km and takes a turn to travel north for another 8 km, the total distance travelled by car shall be 13 km.

Formula:

Distance = speed × time.

Displacement:

Displacement is defined as the change in position of an object. It is a vector  quantity  and has a direction and magnitude. It is represented as an arrow that points from the starting position to the final position.

Example:

If a teacher moves to the right relative to a whiteboard, or a passenger moves toward the rear of an airplane—then the object’s position change.

Speed:

Speed is measured as the ratio of distance to the time in which the distance was covered. Speed is a  scalar  as it has only direction and no magnitude.

Formula:

S =  d/t

Where,

• s is the speed in m.s-1
• d is the distance travelled in m
• t is the time taken in s

Velocity:

The rate of change of the object’s position with respect to a frame of reference and time. The SI unit of it is metre per second (ms-1).It is vector quantity.

Formula: v = distance/time

Example: A manmight drive 100km/hr (the speed) in a northerly direction.

Acceleration:

The rate of change of velocity with respect to time is called acceleration.

It is vector quantity.

Formula:

Acceleration (a) is the change in velocity (Δv) over the change in time (Δt), represented by the equation a = Δv/Δt.

TYPES OF MOTION:

1. Oscillatory motion
2. Rotational motion
3. Translational motion
4.  Uniform motion
5. Non- uniform motion
6.  Periodic motion
7.  Circular motion
8.   Linear motion
9. Projectile

1. Oscillatory Motion:

• A motion which keeps on repeating itself is known as oscillatory motion. It is assumed that oscillatory motion continues forever if there would be an absence of friction, but in a practical situation, it stops eventually by reaching equilibrium.
• The best example of oscillatory motion can be a pendulum of a clock or the string of a musical instrument

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2. Rotational Motion:

• When an item travels along its axis, all of its pieces move for a different distance in a given amount of time, this is known as rotational motion.
• Examples of Rotational motion can be, wheel rotating in a moving vehicle or Earth rotating at its own axis.

3. Translational Motion:

• Transitional motion occurs when all sections of an item move the same distance in the same amount of time. In translation motion, there are two segregations, Curvilinear Motion and Rectilinear Motion.
• Curvilinear Motion: When an object is following a curved path while being in transactional motion, it is said to be in Curvilinear Motion
• Rectilinear Motion: When an object is following a straight-line path while being in transactional motion, it is said to be in Rectilinear Motion.
• Example of translational motion can be a cyclist cycling straight on the path.

4. Uniform Motion:

• Uniform motion occurs when an item moves at a consistent speed in a certain direction at regular periods of time. For instance, while a train moves at a constant speed in a straight-line, it is said to be in Uniform motion. Here, the value of friction would be zero.
• Example of a train can be taken here. A train is said to be in a uniform motion when it is travelling in a straight path at a constant speed.

5. Non Uniform Motion:

• Ifan object is moving at a different velocity at a regular interval of time and is covering a different distance in interval of equal time, then it is called non-uniform motion. Here, the value of acceleration will be non-zero.
• Example of non-uniform motion can be a biker running his bike on a path which is not straight.

6.    Periodic Motion:

• Periodic motion is basically similar to oscillatory motion, which means that motion keeps repeating itself after equal time intervals.
• Example A rocking chair, a bouncing ball, a vibrating tuning fork, a swing in motion, the Earth in its orbit around the Sun, and a water wave..

7. Circular Motion:

• Anobject is said to be in circular motion when the object moves in a circular path constantly. Here, the object speed should be constant.
• Examples of circular motion are carousels or merry-go-rounds in parks, a car going around a roundabout, the moon orbiting around the Earth or the Earth revolving around the Sun.

8. Linear Motion:

• A motion in a straight line, without any divergence is known as linear motion.
• An example of linear motion is an athlete running a 100-meter dash along a straight track. Linear motion is the most basic of all motion.

9. Projectile:

• It is the type of motion which has a horizontal displacement as well as vertical displacement.
• Some examples include meteors as they enter Earth’s atmosphere, fireworks, and the motion of any ball in sports.