Conservation of energy, Physics

CONSERVATION OF ENERGY

1.   Potential energy is, as the word suggests, the energy "locked up" up somewhere and which can perform work. Potential energy Potential energy can be converted into kinetic energy, 1011_kinetic energy.png  . As I showed you earlier, this follows directly from Newton's laws.

 

2. If you lift a stone of mass m from the ground up a distance x, you have to do work against gravity. The (constant) force is mg , and so W = mgx. By conservation of energy, the work done by you was transformed into gravitational potential energy whose values is exactly equal to mgx. Where is the energy stored? Answer: it is stored neither in the mass or in the earth - it is stored in the gravitational field of the combined system of stone+earth.

 

3.  Suppose you pull on a spring and stretch it by an amount x away from its normal (equilibrium) position. How much energy is stored in the spring? Obviously, the spring gets harder and harder to pull as it becomes longer. When it is extended by length x and you pull it a further distance dx, the small amount of work done is dW = Fdx = kxdx. Adding up all the small bits of work gives the total work:

333_kinetic energy1.png

This is the work you did. Maybe you got tired working so hard. What was the result of your working so hard? Answer: this work was transformed into energy stored in the spring. The spring contains energy exactly equal to 1510_kinetic energy3.png.

 

4. Kinetic energy obviously depends on the frame you choose to measure it in. If you are running with a ball, it has zero kinetic energy with respect to you. But someone who is standing will see that it has kinetic energy! Now consider the following situation: a box of mass 12kg is pushed with a constant force so that so that its speed goes from zero to 1.5m/sec (as measured by the person at rest on the cart) and it covers a distance of 2.4m.

Assume there is no friction.

790_kinetic energy2.png

Posted Date: 7/26/2012 3:44:08 AM | Location : United States







Related Discussions:- Conservation of energy, Assignment Help, Ask Question on Conservation of energy, Get Answer, Expert's Help, Conservation of energy Discussions

Write discussion on Conservation of energy
Your posts are moderated
Related Questions
explain and illustrate how pure spectrum is formed

In terms of the wavelength of the pertinent light how thick must the layer of transparent optical coating on a transparent medium be in order to create maximum destructive interfer

A soccer ball is kicked from a 22-m-tall platform. It lands 15 m from the base of the platform. What is the net displacement of the ball?

Determine the mass number of the element? A mass of 25.2 g of an element is known to contain 6.77x 10 23 atoms. What is the mass number of the element? I thought it would be

Chain Reactor: Splitting of nuclei also causes the emission of neutrons. If these neutron cause further fission in the other nuclei and this process continues, then it is known

Motion of simple pendulum. Simple Harmonic Motion:  It is a type of vibratory motion in which body has an immediate acceleration whose magnitude is directly proportional to the

Q. Illustrate What is the geocentric? Answer:- It is science where the earth is the midpoint of the solar system and the other planets and the sun revolve around the earth

basic informations about nicol prism

Which is factual of the light from an actual physical object whose image is formed by a single thin lens? Ans: That's what light perform when it leaves a point on an objec

A reaction is first order in A and second order in B. (a) Write differential rate equation. (b) How is the rate affected if the concentration of B is tripled? (c) How is