Chapter no 7|short Question physics 9thclass||tutoronlines

Properties of Matter

Table of contents:

Number Name of topics
1 Kinetic molecular model of matter
2 Density
3 Pressure
4 Atmospheric pressure
5 Pressure in liquid
6 Up thrust
7 Principle of floatation
8 Elasticity
9 Stress, strain and young’s modulus

Exercise short Questions

Q.1 How kinetic molecular model is helpful in differentiating various states of matter?

Ans.

Q.2 Does there exist a fourth state of matter? What is that?

Ans. Yes, there exists a fourth state of matter called plasma.

At very high temperature, in gases atoms lose their electrons and become positive ions. Thus, the ionic state of matter which consists of ions and electrons is called plasma.

Q.3 What is density? What are its SI units?

Ans. Density is define as its mass per unit volume.

Density=mass of a substance/volume of that substance

Unit:

SI unit of density is kilogram per cubic meter (kgm-3).

Q.4 Can we use a hydrometer to measure the density of milk?

Ans. In order to measure the density of liquids, we use a hydrometer. So we can use a hydrometer to measure the density of milk.

Q.5 Define the term temperature?

Ans. The force acting normally per unit area on the surface of a body is called pressure.

P=Force/Area

P=F/A  unit is Nm-2.

Q.6 Show that atmosphere exerted pressure. ( Write experiment of tin can if ask as a long q)?

Ans. The atmosphere air of Earth consists of gases, vapours and dust particles. Due to the force of gravity these particles exert pressure. So any objects inside the atmosphere experience pressure which is called the atmosphere pressure.

Q.7 It is easy to remove air from a balloon but it is very difficult to remove air from a glass bottle. Why?

Ans. Because the atmospheric pressure act more easily on balloon as compared to glass bottle, so emptying air is easier from balloon than glass bottle.

Q.8 What is barometer?

Ans. The instrument used to measure atmospheric pressure is called barometer. One of the simple barometers is mercury barometer. It consists of a glass tube having a closed end.

Q.9 Why water is not suitable to be used in a barometer?

Ans. Mercury is 13.6 times denser than water. Atmospheric pressure can hold vertical column of water is about 13.6 time the height of mercury column at a place. Thus, at sea level, vertical height of water column would be 0.76m×13.6=10.34m. Thus, we require a glass tube more than 10m long to make a water barometer.

Q.10 What makes a sucker pressed on a smooth wall sticks to it?

Ans. When a sucker is pressed on a smooth surface, the air pressure below it becomes very small ( due to the displaced air) as compared to the air pressure above it. Therefore, it sticks with the smooth surface.

Q.11 Why does the atmospheric pressure vary with height?

Ans. As we go high in the atmosphere, the density of the air becomes low. Due to this reason, atmospheric pressure decreases as we go high.

Q.12 Why does the atmospheric pressure vary with height?

Ans. As we go high in the atmosphere, the density of the air becomes low. Due to this reason, atmospheric pressure decreases as we go high.

Q.13 What does it mean when the atmospheric pressure at place fall suddenly?

Ans. A sudden fall in atmospheric pressure often followed by a storm, rain and typhoon to occur in few hours time

Q.14 What changes are expected in weather if the barometer reading shows a sudden increase?

Ans. A sudden increase in atmospheric pressure means that it will soon followed by a decrease in the atmospheric pressure indicating poor weather ahead. State Pascal’s law. Pressure applied at any point of a liquid enclosed in a container, is transmitted with out the loss to all other parts of the liquid.

Q.15 Explain the working of hydraulic press?

Ans. See next book Q.6 long question.

Q.16 What is elasticity?

Ans. The property of a body to restore its original size and shape as the deforming force ceases to act is called elasticity.

Q.17 State Archimedes principle?

Ans. When objects is totally or partially immersed in a liquid, an up thrust act on it equal to the weight of the liquid it displaces.

Q.18 What is up thrust? Explain the principle of floatation?

Ans. An upward force which acts on an object kept inside a liquid. As a result an apparent loss of weight is observe in the object. This upward force acting on the object is called the up thrust of the liquid.

Q.19 Explain how a submarine move up the water surface and down into water?

Ans.

Q.20 Why does a piece of stone sink in water but a ship with a huge weights float?

Ans. The up thrust force on stone is much smaller than its weight because weight of the water displaced under stone is very small. While the ships are designed in such a way weight of the water displaced by them is greater than their weight. So up thrust force in case of ships is greater than their weights. So ships float on the surface of water.

Q.21 What is Hooke’s law? What is mean by elastic a limit?
Ans. Hooke’s law:

The strain produced in a body by the stress applied to it is directly proportional to the stress within the elastic limit of the body.

Elastic limit:

It is a limit within which a body can recovers its, volume or shape after deforming force is removed is called elastic limit. When a body crosses this limit, it is permanently deformed and is unable to restore its original state after the stress is removed.

Q.22 Take a rubber band. Construct a balance of you own using a rubber band. Check its accuracy by weighting various objects?

Ans. Take a rubber band hang it with a hook. Then pointer is attached at the lower end of it with scale in front of pointer. Different known weights are suspend one by one at the lower end of the rubber band. Mark the pointer position for each known weight. It is called calibration of scale for weight measurements. This makes a balance for weight measurements.

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