Chapter 7 Physics Class 9 Notes

Complete Notes of Chapter 7 Physics Class 9 Notes Properties of Matter Notes in 9th Class Physics English Medium written by Professor Tayyab Shahzad. These computerized notes are very helpful in the preparation of Properties of Matter Notes for students of the Chapter 7 Physics Class 9 Notes these are according to the paper patterns of all Punjab boards.

• Here are the detailed 9th class physics chapter 7 notes to help you prepare for your exams.
• Properties of Matter Exercise Multiple Choice Questions ( MCQs ) with correct Answers
• Properties of Matter Exercise Short Questions with Answers
• How kinetic molecular model of matter is helpful in differentiating various states of matter?
• What is meant by density? What is its SI unit?
• Does there exist a fourth state of matter? What is that?
• Can we use a hydrometer to measure the density of milk?
• Show that the atmosphere exerts pressure.
• Define the term pressure.
• It is easy to remove air from a balloon but it is very difficult to remove air from a glass bottle. Why?
• Why water is not suitable to be used in a barometer?
• What is a barometer?
• What makes a sucker pressed on a smooth wall sticks to it?
• What does it mean when the atmospheric pressure at a place falls suddenly? 
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• Why does the atmospheric pressure vary with height?
• What changes are expected in weather if the barometer reading shows a sudden increase?
• Explain the working of a hydraulic press.
• State Pascal’s law
• What is meant by elasticity?
• What is up thrust? Explain the principle of floatation.
• State Archimedes principle
• Explain how a submarine moves up the water surface and down into the water.
• What is Hooke’s law? What is meant by elastic limit?
• Why does a piece of stone sink in water but a ship with a huge weight floats?
• Take a rubber band. Construct a balance of your own using a rubber band. Check its accuracy by weighing various objects. 
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• Important values and units and Important Formulas
• Properties of Matter Exercise Numericals with Solutions
• DENSITY: Is an iron object heavier than that of wood? Not necessary. It depends upon the quantity of iron and wood you are comparing. For example, if we take equal volumes of iron and wood, then we can easily declare that iron is heavier than wood. The density of a substance is the ratio of its mass to that of its volume. Thus
• "Density of a substance is defined as its mass per unit volume".  Density =  mass of a substances / Volume of that substances
• SI unit of density is kilogramme per cubic metre (kgm^-3). We can calculate the density of a material if we know its mass and its volume. For example, the mass of 5 litre of water is 5 kg. Its density can be calculated by putting the values.
• PRESSURE: Press a pencil from its ends between the palms. The palm pressing the tip feels much more pain than the palm pressing its blunt end. We can push a drawing pin into a wooden board by pressing it by our thumb. It is because the force we apply on the drawing pin is confined just at a very small area under its sharp tip. Thus pressure is defined as 
• "The force acting normally per unit area on the surface of a body is called pressure". Pressure = Force / Area  , P = F / A
• Pressure is a scalar quantity. In SI units of pressure is Nm^-2 also called pascal (Pa). Thus 1 Nm^-2 = 1 Pa
• Atmospheric pressure class 9: The Earth is surrounded by a cover of air called atmosphere. It extends to a few hundred kilometres above sea level. Just as certain sea creatures live at the bottom of ocean, we live at the bottom of a huge ocean of air. Air is a mixture of gases. The density of air in the atmosphere is not uniform. It decreases continuously as we go up. Atmospheric pressure acts in all directions. What the girl is doing? Soap bubbles expand till the pressure of air in them is equal to the atmospheric pressure. Why the soap bubbles so formed have spherical shapes? Measuring atmospheric pressure class 9