Motion in Physics - Definition, FAQs

Edited By Vishal kumar | Updated on Sep 24, 2024 12:55 PM IST

What is motion in Physics? What is meant by motion? Define motion in Physics

Motion definition physics: Motion in physics, movement is a phenomenon in which an object over time changes position. In terms of movement, distance, speed, acceleration and time, motion is described quantitatively.

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Motion in Physics - Definition, FAQs

Three laws of motion

The movement of huge bodies is described in physics by two related sets of mechanical rules. Classical mechanics describe motion in Universe for all huge as well as recognisable items

The three rules of classical mechanics were formulated by Newton as well as Euler historically:

The three equations of motion are as follows:

$\\1. \ v=u+at \\2.\ S=ut+\frac{1}{2}at^2 \\3.\ V^2=u^2+2as$

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Newton 1st law of motion or law of inertia.

"Everything continues to be in its state of rest or uniform motion along a straight line unless driven to act otherwise by some other body," Newton's first law states. The property of a body that resists changes in its state of rest or uniform motion is known as inertia. If the total external force is zero, an object in uniform motion will remain in uniform motion, and an object at rest will remain at rest.

Newton's second law of motion

The vector sum of the forces F on an object in an inertial reference frame equals the object's mass m multiplied by its acceleration.

F=ma

It is a vector quantity

SI Unit Newton (N)

Newton third law of motion

When one body puts a force on another, the second body simultaneously exerts a force on the first body that is equal in size and opposite in direction.

Action = -reaction

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Translational motion

The driving force F is balanced in translational motion by a resisting force F_r generated by the driven machine and an inertia force Ma generated by the change in speed, or

F-F_r=Ma=Mdv/dt

Where M is the mass given in kilogrammes the velocity v in metres per second, the acceleration an in metres per second², and the force F in Newton (N)

Oscillatory motion

Periodic or oscillatory motion is defined as a motion that repeats itself. Due to a restoring force or torque, an object in such motion oscillates around an equilibrium position. No matter which direction the system is moved, such force or torque tends to restore (return) the system to its equilibrium position.

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Rotational motion

In rotational motion, the driving torque T_m (often generated by an electric motor) is balanced by a resisting torque T_L (typically generated by the load and referred to as the motor shaft) and inertia or dynamic torque Jdω/dt.

T_M-T_L= Jdω/dt.

Where J is the moment of inertia given in kg*m² It is also known as flywheel

Torque or moment, where T is the torque in N*m. The signs to be associated

With T_M and T_L in Eq. (2) are determined by the driving motor's operating

regime and the nature of the load torque.

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Relativistic mechanics

Modern kinematics evolved from the study of electromagnetic and refers to all velocities v in terms of their ratio to the speed of light c. Velocity is thus understood as rapidity, the hyperbolic angle for which the hyperbolic tangent function tan h = v/c. Acceleration, or a change in velocity, affects rapidity according to Lorentz transformations. This branch of mechanics is known as special relativity. W. K. Clifford and Albert Einstein both attempted to incorporate gravity into relativistic mechanics. The development employed differential geometry to describe a curved cosmos with gravity; the research is known as general relativity.

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