Mechanical Energy Definition

What is mechanical energy in simple definition?

Mechanical energy (Emech) is the energy that is connected to an object’s motion and location in a force field, such as the gravitational field. The two types of mechanical energy — transient and stored — can be distinguished from one other. The energy that is kept inside a material or object is known as stored energy.

Two types of mechanical energy may be stored: kinetic and potential energy.

The energy held in an item when it is subject to a certain conservative force is known as potential energy, or U. The gravitational potential energy of an item, which is affected by its mass and the separation from the center of mass of another object, is an example of a common kind.

The energy that an item stores due to its motion are known as kinetic energy or K. The capacity of a moving item to interact with other things when it collides with them relies on the speed of the object.

Conservation of Mechanical Energy

The conservation of mechanical energy idea was first stated:

When a particle is subjected to solely conservative forces, its total mechanical energy — which is calculated as the product of its potential and kinetic energies — remains constant. A system is said to be isolated if there is no outside factor causing energy changes. If an item is subject to just conservative forces and U represents the potential energy function for all conservative forces, then,

Emech = U + K

The location of an item under the influence of a conservative force determines the potential energy, It is characterized as the object’s capacity to perform work, which rises when the object is pushed against the direction of the applied force.

Gravitational potential energy is the energy associated with a system consisting of Earth and a nearby particle.

The capacity of a moving item to exert force on other things when it collides with them is known as kinetic energy, abbreviated K, and it relies on the speed of an object.

K = ½ mv2

The definition of “Emech” given above (Emech = U + K) assumes that friction and other non-conservative forces are absent from the system. When a conservative force moves an item from one location to another, the work it does is independent of the path, which is the difference between a conservative force and a non-conservative force.

Frictional forces and other non-conservative forces are always present in reality, but they frequently have such negligible impacts on the system that the idea of mechanical energy conservation can serve as a reasonable approximation. As an illustration, the frictional force operates to lower the mechanical energy in a system, making it a non-conservative force.

Keep in mind that not all non-conservative forces result in a decrease in mechanical energy. A non-conservative force modifies mechanical energy. Non-conservative forces also include those that increase total mechanical energy, such as the force produced by an engine or motor.

Block Sliding Down a Frictionless Incline Slope

The 1 kilogram block has potential energy mgH and kinetic energy equal to 0. It begins at height H (let’s say 1 m) above the ground. Without creating any friction, it falls to the ground, arriving at rest with kinetic energy K = 1/2 mv2 and no potential energy. Determine the block’s kinetic energy and velocity at rest.

Emech = U + K = const
=> ½ mv2 = mgH
=> v = √2gH = 4.43 m/s
=> K2 = ½ x 1 kg x (4.43 m/s)2 = 19.62 kg.m2.s-2 = 19.62 J

Pendulum

Consider a pendulum (a ball with mass m hung on a string with length L that has been pulled up to raise the ball to a height H > L above the point at which the stretched string motion of the ball is at its lowest. The pendulum is subject to a conservative gravitational force, with low frictional forces at the pivot and air drag.

Since it will be moving at its fastest and closest to the Earth when it is vertical, the pendulum will have the most kinetic energy and the least potential energy. On the other hand, because it is moving at a standstill and is furthest from Earth at these places, it will have the least kinetic energy and most potential energy at these points.

Small swings have roughly the same swing time regardless of their size. In other words, amplitude has no effect on the period.