Difference between Force and Energy

Energy is one of the fundamental characteristics of any and every object. Every object possesses some energy in one form or other. It is a well-known fact that Energy cannot be created nor can be destroyed but can only change form. A stationary object has a potential energy while a moving object has a kinetic energy. The energy can be defined, in terms of equation, as;

E = m c2;

M – mass of object;

C = Velocity of light.

The energy is measured in Joule (Newton – meter) in S.I. units. The energy can also be defined as work done by one object on another object to move it for one unit distance with a force of 1 Newton. Therefore the unit of energy is Newton – meter or Joule. This unit is also the unit of work and heat dissipated by an object.

Although the work and energy have common units however the energy is necessary for accomplishing the work on the object. If the object does not possess any energy then the work cannot be done on the object. 

Force is a pressure exerted or work done by an external entity to make an object change its state. For example a stationary object may change its position from stationary to moving when an external force is applied to it. In this case the stationary object which possesses potential energy has its energy converted to the kinetic energy by the application of the external force.

The force can be defined, in terms of equation, as;

F = m * a;

M = mass of object;

A = Acceleration of the object.

The force is measured in Newton in S.I. units.

The force and energy are interrelated, since from the above discussion it is cleared that the energy changes its form after an external force is applied to it. The famous energy equation e = mc2, is only possible if the relation between the force and the energy exists as discussed previously otherwise the equation has no relevance to study.

In simple words we can say that some force need to be applied to change the energy state of the object. The force disturbs the equilibrium and hence the transformation of energy from one form to another.

From the units of both the force and energy it is clear that the energy is the force per unit of length, which means that the energy is equal to force for a unit meter.

Example of force:

If a body of mass 15 kg is accelerating with 20 meter per second square, find the force experienced by the body?

We know that the force is the product of the mass and acceleration and hence the force on the body would be;

F = 15 * 20 = 300 Newton.

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From Encyclopedia


energy in physics, the ability or capacity to do work or to produce change. Forms of energy include heat , light , sound , electricity , and chemical energy. Energy and work are measured in the same units—foot-pounds, joules, ergs, or some other, depending on the system of measurement being used. When a force acts on a body, the work performed (and the energy expended) is the product of the force and the distance over which it is exerted. Potential and Kinetic Energy Potential energy is the capacity for doing work that a body possesses because of its position or condition. For example, a stone resting on the edge of a cliff has potential energy due to its position in the earth's gravitational field. If it falls, the force of gravity (which is equal to the stone's weight; see gravitation ) will act on it until it strikes the ground; the stone's potential energy is equal to its weight times the distance it can fall. A charge in an electric field also has potential energy because of its position; a stretched spring has potential energy because of its condition. Chemical energy is a special kind of potential energy; it is the form of energy involved in chemical reactions. The chemical energy of a substance is due to the condition of the atoms of which it is made; it resides in the chemical bonds that join the atoms in compound substances (see chemical bond ). Kinetic energy is energy a body possesses because it is in motion. The kinetic energy of a body with mass m moving at a velocity v is one half the product of the mass of the body and the square of its velocity, i.e., KE = 1/2 mv2 . Even when a body appears to be at rest, its atoms and molecules are in constant motion and thus have kinetic energy. The average kinetic energy of the atoms or molecules is measured by the temperature of the body. The difference between kinetic energy and potential energy, and the conversion of one to the other, is demonstrated by the falling of a rock from a cliff, when its energy of position is changed to energy of motion. Another example is provided in the movements of a simple pendulum (see harmonic motion ). As the suspended body moves upward in its swing, its kinetic energy is continuously being changed into potential energy; the higher it goes the greater becomes the energy that it owes to its position. At the top of the swing the change from kinetic to potential energy is complete, and in the course of the downward motion that follows the potential energy is in turn converted to kinetic energy. Conversion and Conservation of Energy It is common for energy to be converted from one form to another; however, the law of conservation of energy, a fundamental law of physics, states that although energy can be changed in form it can be neither created nor destroyed (see conservation laws ). The theory of relativity shows, however, that mass and energy are equivalent and thus that one can be converted into the other. As a result, the law of conservation of energy includes both mass and energy. Many transformations of energy are of practical importance. Combustion of fuels results in the conversion of chemical energy into heat and light. In the electric storage battery chemical energy is converted to electrical energy and conversely. In the photosynthesis of starch, green plants convert light energy from the sun into chemical energy. Hydroelectric facilities convert the kinetic energy of falling water into electrical energy, which can be conveniently carried by wires to its place of use (see power, electric ). The force of a nuclear explosion results from the partial conversion of matter to energy (see nuclear energy ).

From Yahoo Answers

Question:I have a test on Friday and I need to get this question clearly awnsered. What is the difference between force and energy. My teacher said Energy- Ability to do work ; Force- Push or pull on an object. What is the difference. And also I'd appreciate a better explanation of Energy. I need to have the definitions. Not what comes first. Help me out here plzzzz :) Can u plz not make it complicated, Im a 7th grade student!!!!!!!!!!

Answers:Force is an influence on an object with mass that results in a change in velocity. Units are (for example) newtons or lbf. Work can be thought of as a measure of force acting over a distance, so if you increase either the force or the distance that it is applied, then the work increases. Units are newton - meters = joules or inch - lbf. Energy is a measure of the amount of work that an object is capable of doing. It is evaluated using the same units as work - in a sense, the two are equivalent. Energy is generally considered as either kinetic, potential, or heat energy. ADDED (and edited): I will try, Mustafa. Anything you do to an object to make it start to move or stop moving is called a force. You can push it, or you can blow on it, or you can hit it with a hammer. Energy is what you do to that object to make it move for a certain distance. For example, if I push on an object with 10 lbf it might slide an inch or so. I will be pushing with a force against the object, but using very little energy. If I push on it with 10 lbf and make it move for 50 feet (keep pushing), then I am using more energy to apply the SAME force for that distance. That energy can come from the food going to my muscles, or the gasoline burned in a car, or by a weight that swings down from a great height on a pendulum. Does this help?

Question:friends, electric potential is defined as the work done to bring a unit positive charge from infinity to that point against electric forces. electric potential energy is the work done to assemble the charge. What is the difference between electric potential and electric potential energy?

Answers:Electric potential is the potential energy per unit charge, just as electric field is the force per unit charge. It's a way to describe the system independent of the "test charge". So if it takes 10 eV of energy to move a single elementary charge (like a proton) from A to B, we say the difference in the proton's potential energy is 10 eV between those points. But independent of the proton, we say the difference in potential between those two points is 10 Volts. The charge we're moving has potential energy U. The field we're moving it through has potential. V = U/q, or U = qV.

Question:I am told planetary motion involves a central force. Is this also a centripetal force? If so, why is a central force different to a centripetal force?

Answers:use perhaps the Riemann's dzeta function

Question:for e.g when the object is falling towards the ground and when the object is stable on the ground...( can i explain it in terms of change in velocity , acceleration and weight force

Answers:I think she is referring to the difference between an objects weight(force) due to gravity and the force produced on an object during acceleration. There is no real difference other than the effect that produces the force. Einstein's elevator thought experiment showed us that an observer in a stationary elevator on earth would not be able to tell the difference if he were in an elevator in space (no gravity) moving at an acceleration equal to that of earth's.

From Youtube

Real World: Work, Force, Energy and Motion :In this NASA video segment learn how to calculate the force, energy, motion and work of an object. Find out how these properties compare with one other. Color animation is used to demonstrate how to calculate each property using proper units of measurement. This video segment also explains the difference between potential and kinetic energy as well as how to calculate gravitational potential energy. Examples are provided throughout the segment for clarification.