Class 9th Physics Chapter 6 Question Answer

Complete Notes of Class 9th Physics Chapter 6 Question Answer Work and Energy class 9 Numericals of 9th Class Physics Urdu Medium written by Sir Fahad Abbas Suib. These computerized notes are very helpful in the preparation of Work and Energy class 9 Numericals for students of the Class 9th Physics Chapter 6 Question Answer these are according to the paper patterns of all Punjab boards.

• Important Values and Important Formulas
• Work and Energy Exercise Numericals with Solutions in Urdu 
• KINETIC ENERGY CLASS 9: Moving air is called wind. We can use wind energy for doing various things. It drives windmills and pushes sailing boats. Similarly, moving water in a river can carry wooden logs through large distances and can also be used to drive turbines for generating electricity. Thus a moving body has kinetic energy, because it can do work due to its motion. The body stops moving as soon as all of its kinetic energy is used up.
• "The energy possessed by a body due to its motion is called its kinetic energy". Exampals: Energy of the wind moves the sailing boats. Running water possesses energy.
• Consider a body of mass m moving with velocity v. The body stops after moving through some distance S due to some opposing force such as force of friction acting on it. The body possesses kinetic energy and is capable to do work against opposing force F until all of its kinetic energy is used up.
• POTENTIAL ENERGYCLASS 9: Often a body has the ability to do work although it is at rest. For example, an apple on a tree is capable to do work as it falls. Thus, it possesses energy due to its position. The kind of energy which a body possesses due to its position is called its potential energy.
• "The energy possessed by a body due to its position is known as its potential energy". Exampals: Stored water possesses potential energy due to its height. A hammer raised up to some height has the ability to do work because it possesses potential energy. A stretched bow has potential energy due to its stretched position. When released, the stored energy of the bow pushes the arrow out of it.
• Elastic potential energy class 9: The energy present in the stretched bow is called elastic potential energy. The potential energy possessed by a hammer is due to its height. The energy present in a body due to its height is called gravitational potential energy. Let a body of mass m be raised up through height h from the ground. The body will acquire potential energy equal to the work done in lifting it to height h. P.E = mgh
• FORMS OF ENERGY CLASS 9: Energy exists in various forms. Some of the main forms of energy are Mechanical Energy, Heat Energy, Electrical Energy, Sound Energy, Light Energy, Chemical Energy and Nuclear Energy
• MECHANICAL ENERGY CLASS 9: The energy possessed by a body both due to its motion or position is called mechanical energy. Water running down a stream, wind, a moving car, a lifted hammer, a stretched bow, a catapult or a compressed spring etc. possess mechanical energy. 
• HEAT ENERGY CLASS 9: Heat is a form of energy given out by hot bodies. Large amount of heat is obtained by burning fuel. Heat is also produced when motion is opposed by frictional forces. The foods we take provide us heat energy. The Sun is the main source of heat energy.
• ELECTRICAL ENERGY CLASS 9: Electricity is one of the widely used form of energy. Electrical energy can be supplied easily to any desired place through wires. We get electrical energy from batteries and electric generators. These electric generators are run by hydro power, thermal or nuclear power.
• SOUND ENERGY CLASS 9: When you knock at the door, you produce sound. Sound is a form of energy. It is produced when a body vibrates; such as vibrating diaphragm of a drum, vibrating strings of a sitar and vibrating air column of wind instruments such as flute pipe etc.
• CHEMICAL ENERGY CLASS 9: Chemical energy is present in food, fuels and in other substances. We get other forms of energy from these substances during chemical reactions. The burning of wood, coal or natural gas in air is a chemical reaction which releases energy as heat and light. Electric energy is obtained from electric cells and batteries as a result of chemical reaction between various substances present in them. Animals get heat and muscular energy from the food they eat.