The nature of energy
Energy is the capacity to do work. When force is applied to an object to make it move then work has taken place.
Forms of energy
Heat energy: it can be used in chemical reaction. It also change solid to liquid through heating.
Mechanical Energy: it is used to move the blades of fan even the axles of a car.
Nuclear energy: it used to provides energy to power a submarine or to produce electricity.
Electrical energy: can be used to produce light, turn a motor, or store data on hard drive.
Light energy: it produce energy used during photosynthesis. It is also used to create an image.
Chemical energy: it can be found in food (it gives us energy) , in gas, coal, wood, or the oil we heat (it heats our building by keep it warm) in batteries (when connected in circuit, it gives electricity).
Law of conservation of energy
The law of conservation of energy states that energy cannot be created not destroyed; but changed in form. For example:
Electrical energy is in homes to provides it energy like in case of Electric stove, it also lights our bulb and other appliances.
There are two types of energy
Which are as follows:
- Potential energy(positioning)
- And kinectic energy(motion)
Potential energy can be detectable by it’s position before a action is taken. E.g. a ball is about to be hit by an object; at that point the object has potential energy because of its position. But when that object hit the ball kinectic energy has taken place already.
Note that energy is measured in joules. Power is the rate at which work is done. Power is measured in watts.
Through Albert Einstein a physicist, the relationship between energy and mass was discovered and he expressed it in the equation. E= mc2, in which E = energy, m = mass, c= the speed of light.
Questions
1. From the options below which one of them states the conservation of energy correctly?
A. Energy cannot be created or destroyed, but can only change in form
B. Energy cannot be created, destroyed, or changed in form
C. Potential energy is the energy of position while kinetic energy is the energy of motion.
D. Kinetic energy is the energy of position while potential energy is the energy of motion.
Ans= A
2. ……… can be used in chemical reaction?
A. Nuclear energy
B. Mechanical Energy
C. Heat energy
D. Light energy
Ans= C
3. Electrical energy can be ……… energy in light bulb?
A. Sound
B. Light
C. Mechanical
D. Work
Ans= B
4. Energy is measured in ……..?
A. Watts
B. Metre
C. Joules
D. Power
Ans= C
5. Which of the following explains Einstein’s equation E=mc2 ? A. The relationship between energy and energy B. The speed of light on a vacuum C. The relationship between energy and mass D. The relationship between electrical energy and nuclear energy.
Ans= C