Saturday, September 21, 2013

The Law of Conservation of Energy

Law of conservation of energy states that energy can neither be created nor destroyed. Energy can only be conserved. Take the case of throwing a ball upwards. What are the forces that act on the ball?. One is the weight of the ball that causes it to be pulled down. The next is the upward force on the ball that is provided when the ball leaves the hand.

How far will the ball travel upwards?. This question can be answered easily by using the law of conservation of energy. When the ball is thrown up the energy it has is due to its velocity or kinetic energy. During its motion upwards the ball has both kinetic energy and potential energy. The speed or the velocity of the ball will be maximum when it leaves the hand and will be zero when it reaches the maximum height. At any point in time the velocity will reduce slowly ( this is called as retardation as opposed to acceleration where the veolocity increases continuosly). The maximum height travelled by the ball can then be determined by equating potential energy at the destination ( here Kinetic energy is equal to 0 as the ball is at rest), to the kinetic energy at the start of the motion ( here the potential energy is equal to 0).

Without the force of gravity we would not be attracted downwards to our planet and so we will be always floating upwards. The LCE can be used to make important derivations even the object that is thrown upwards does not go up in the vertical direction ( or goes in a parabolic path).

Imagine a marble that is just rolling downwards on a slope and is made to go into a circular ring, energy is conserved in this case as well. One can use the Law of conservation of Energy to determine the maximum time that the marble will be inside the circular hoop.

How are we able to walk?. We walk because of the frictional force that exists between the foot and the earths surface. If friction did not exist we would not be able to stop walking. A ball that is rolling on the floor stops at some point of time due to friction between the earths surface and the ball.

Law of Conservation

When a roller skater rotates on her scates, she travels faster is she makes a circle in a smaller radius. This is because a quantity termed as Angular Momentum (AM, ang Mom) is conserved in the process. Angular momentum is given by the equation = I * w * w. I is termed as the Moment of inertia. The angular velocity is a vector quantity implying that localised direction of travel is important in a circular motion.

When a scater suddenly reduces her radius of motion, her moment of inertia decreases. In order for the angular momentum of travel to be conserved the velocity increases. In other words if she goes around in a smaller circle her speed increases.

Let us take the case when she travels in a bigger circle than before. In this case too, angular momentum is conserved. In this case the moment of inertia increases. So in order for the total AM to be conserved her speed decreases.

This law is termed as the law of conservation of ang mom it applies to all objects that are rotating in a circular motion.

An analogy to the same law is the law of conservation of momentum which applies to motion in straight lines. In this case the momentum of the system of bodies that are colliding is conserved. So the momentum before the collision is MV + M1V1 where M and M1 are two different masses which travel at different speeds. So the total momentum of the system is conserved. AM and linear momentum are vectors implying that the quantity is dependent upon the direction.

Concepts of Labour Law and the Employment Contract

In the past, the common law appeared to value the need for an employee to be loyal and obedient and there was no responsibility on the part of the employer to ensure that the worker had access to economic welfare and job security. However, it appears that the common law also imported the notion of an implied obligation of mutual trust and confidence between employers and employees and that this pattern is evidenct in the jurisprudence of courts in the United States. It is argued by many legal scholars that the pattern of employment law as it is dealt with by the common law tends to favour employers in that labour unions are regulated with an assumption of distrust and that the law tends to adopt the values of conservative political participants such as journalists, politicians and senior bureacrats.

It is often referred to as the unitary view of labour relations which is contrasted with some of the other views such as the pluralist approach which recognises that management and labour may and do have different and competing interests because employers are ultimately concerned to make profit whereas employees are most focused on having the best possible working conditions, a healthly and safe work environment and occupational security. The pluralist view is sometimes extended to what is termed the radical view of labour relations which is associated with Marxist economic theory and posits that capitalism is endemically prone to industrial conflict owning to the exploitative nature of economic relationships in a captialist system. However, many scholars seem to accept that both the radical and libertartian view of labour relations are too extreme to accurately reflect reality.

In the modern super flexible economy where persons can and do change careers quickly and regularly, there are few workplaces with standard hours of work and there are increasing numbers of people engaged in work from home via the phenomenon of teleworking, the old concepts of labour law are beginning to become outdated. In previous times the concept of labour law was that a person would do work for an employer in a single location, in a single occupation for a single employer. Now workers tend to work a range of employers at once, often on a part time or casual basis. Also, there are now a large number of people who view themselves as self-employed. These trends are explained by the preceived desire of workers to claim flexibility in their working arrangements. It also means that greater efficiency can be gained from the power of technology to allow teleworking. However, despite all of these changes, there has not been a repudiation of the need for there to be a written employment contract between an employer and employee.