Understanding Different Forms of Energy and Conversion Processes

Concept of energy Forms of energy Conversion of energy Concept of work done Concept of power used by a body

Energy is defined as the ability to do work. Humans need energy to run, walk, jump, eat, wash, play, talk, fly etc. No action can take place without energy been used. Though energy can not be seen physically but it can however be measured with an instrument called Energy Meter. The unit of energy is joule. The higher the energy a person or an object has, the higher the amount of work the person or object can do.

Heat energy a body. It can be obtained from pressing iron, cooker, rubbing two bodies together, soldering iron etc. Mechanical energy potential for motion. Example falling objects, flowing objects etc. It is classified into potential and kinetic energy. Electrical energy: electrical appliances such as radio, fan, television etc. We obtain it from public power supply and generators at homes & industries. Heat energy: it leads to the rise in temperature of Mechanical energy: it is energy of motion or Electrical energy: it is the energy used to operate

Sound energy: vibrates in the air. It comes from talking, clapping, loud speakers striking the musical instruments etc. Sound energy travels through the air. Light/Solar energy: comes from the sun and is released through its rays. It enables photosynthesis which in turn leads to production of food by plants. It also generates heat. Sound energy: it stimulates our ear and Light/Solar energy: it a form of energy that

Nuclear from the split of atoms. This is done using an instrument called cyclotron. Nuclear energy is used to generate power in a nuclear power generating station. Nuclear energy energy: : it is a form of energy gotten

Naturally energy is never destroyed but can only be converted from one form to another. In some cases we store the energy when they are not required at the moment. When a car is parked, it possesses potential energy, when it moves the potential energy is converted to mechanical energy. The chemical energy in the petrol stored in the tank of the car is burnt to produce heat energy which is converted to mechanical energy that moves the car.

Work is said to be done when force has been used to move an object through a distance. Work is done when energy is used up. The force applied determines the amount of work done and distance moved is in the direction of the force applied. Work done is the product of Force and Distance. Work done is measured in joule or Nm

Example 1 15N moves a body through a distance of 20m Solution = 15N 20m = 300Nm (300J) Example 1: calculate the work done when a force of Solution: work = force distance Example weighs 40kg in pushing a table of mass 50kg through a distance of 20m. (g=10m/s ) Solution: work = force distance force= mass gravity Total mass = 40kg + 50kg=90kg force = 90kg 10 = 900N Distance = 20m Work done = 900N 20m =18000Nm (18000J) Example 2 2: calculate the work done by Emeka who

Power is the rate at which work is done. A powerful person takes less time to do a work than a weak person Power is therefore determined by the work done and the time taken Power=work done/time taken(seconds) The unit of power is watts, it is measured with an instrument called wattmeter. NB: In the industry, power is measured in Horsepower(hp) as such 1hp=746watts

Example: If a machine uses a force of 90N to carry a load through a distance of 2km in 3minutes. calculate the power of the machine. Solution: power = work done/time taken Work done = 90N 2 1000 = 180000J Time taken = 3 60 = 180 seconds Power = 180000J/ 180 seconds= 1000watts=1kw

Briefly explain the concept of energy List the forms of energy and explain them Can energy be destroyed? Support your answer with explanations Briefly explain when work can e said to be done What is power? Calculate the work done and power, if it takes a boy weighing 33kg 4minutes to pull a bag whose mass is 72kg through a distance of 300meters.