Motion

Motion is a change of position. Most motions are complex. Some objects can move in a straight line, some can take a circular path, some can rotate, and some can vibrate. In addition to this, there may be situations involving a combination of these.

Describing Motion:

Motion can be described as a distance traveled or a displacement.

• Distance: The total movement of an object with no reference to the direction
• Displacement: Describes the general motion of an object and locates its end position about its initial position at a specific point in time. The shortest distance is measured when the object starts moving to the final destination

The point needs to be noted that the numerical value or the Magnitude of the displacement may be zero, but the distance covered can never be zero.

Types of Motion:

• Uniform motion: An object is said to be in uniform motion when it covers an equal amount of distances in the equal intervals of time. Example: Trail of students walking in a straight line
• Non-uniform motion: Non-uniform motion is, if the object covers unequal distances in equal amounts of time.  Example: A car moving straight at a steady speed

Speed:

• It is the distance traveled by the object per unit of time
• If an object covers a distance in time t, then its speed v is,

V = st

• Meter per second is known to be the SI unit of speed

• It is represented by the symbol m s–1 or m/s
• Other units include centimeters per second (cm s–1) and kilometers per hour (km/ h) 

• To specify the speed of an object, only its magnitude is required. The speed of an object does not have to be constant
• In most cases, objects are in non-uniform motion.  So, we describe the rate of motion for such motion by finding the average speed
• Average speed: The total distance traveled divided by the total time taken gives the average speed of an object

Average speed = Total distance travelled / Total time taken

Velocity:

• It is the speed of an object moving in a defined direction
• The velocity can be changed by changing the speed, direction, or both for an object. Hence it may be uniform or change as per the condition
• When an object is moving at a variable speed along a straight line, the magnitude of its rate of motion can be expressed in average velocity
• In case the velocity of the object changes at a uniform rate. The average velocity is given by the arithmetic mean of initial velocity and final velocity for a given period. That is,

Average velocity = (Initial velocity + Final velocity)/ 2, or

vav = (u + v)/2

Here, vav is the average velocity, u is the initial velocity and v is the final velocity of the object

• Both speed and velocity have the same units, i.e., m s^–1 or m/s

Acceleration:

• The measure of the change in the velocity of an object per unit time

When the velocity of an object changes from an initial value u to the final value v within time t, then the acceleration of the object  is expressed as:

Acceleration = Change in velocity / Time taken, or

a = v – ut

• Acceleration is considered positive if it is in the direction of velocity and negative when it is opposite to velocity
• The SI unit of acceleration is known to be m s^–2 
• Types of acceleration:

• Uniform acceleration: If an object traveling in a straight line experiences an increase or a decrease in its velocity by equal amounts in equal intervals of time, then its acceleration is said to be uniform. For example, the motion of a freely falling body experiences uniform acceleration
• Non-uniform acceleration: If an object’s velocity changes at a non-uniform rate, the object can travel with non-uniform acceleration

Uniform Circular Motion:

• Uniform circular motion is when an object moves in a circular path at a uniform speed
• Examples are the motion of the moon and the earth, a cyclist on a circular track at a constant speed, and a satellite that moves on a circular orbit around the earth

Conclusion :

Here, we discussed motion and different types of motion. We also elaborated terminology related to the motion of an object. Types of linear motion are also described with some examples. Different equations related to the motion of an object moving in a straight line are noted.

The displacement is determined only by the endpoints, but the path length is determined by the actual path. In general, the amount of displacement differs depending on the route length traversed by the item between two places. Furthermore, the two amounts are identical only if the object’s path of motion remains constant. In addition, in all other circumstances, the route length is higher than the amount of displacement. Consequently, there is no option of axes in the vector equation. However, they can be resolved along any two separate axes.)