Physics IX Notes Chapter 7 Properties of Matter
Q.1 explains the
kinetic molecular model of matter?
Ans. kinetic molecules model of matter:- according to this theory
matter consists of small particles called modules. Modules are its made of small a particle called atoms. These molecules are always I state of motion. Their the motion may be linear vibrational or rotational and this motion is increased
with an increase in temperature, there is a force of attraction between the
molecules which depend upon the distance between them their kinetic energy is
due to their motion and potential energy is due to the force of attraction between
them.
Q.2 explains
the states of matter on the bases of a molecular model of matter?
Ans. State
of matter explained below on the bases of molecular theory?
1.
Solids:-
i.
solids have defined shape and a definite volume.
ii.
In solids, molecules cannot transfer from one place to
another.
iii.
Their molecules perform the vibratory motion.
iv.
Their molecules are increased with an increase in
temperature.
2.
Liquids:-
I.
Liquids have a definite volume but no definite pe.
II.
Molecules in liquids are loosely bided to each other.
III.
In liquids, molecules can transfer from one place to
another.
IV.
Force of attraction b/w molecules is weaker than
solids.
V.
Their K.E increase with an increase in temperature.
3. Gases:-
i.
they have neither definite shape nor volume.
ii.
Their molecules are at a large distance from one
another.
iii.
Their molecules can move freely and perform random
motion.
iv.
Force of attraction b/w molecules in temperature.
4.
Plasma:- this is the 4th
state matter which is found in the ionized state it is called plasma exist in sun.
Q.3 Define and explain “Density”?
Ans.
Density:- the mass f unit volume is called density it is denoted by (Rho).
Explanation:-if
mass of a body is “m” and volume of that body is “v” then we can write its
mathematical form as;
From its mathematical form, it is clear that density the intermolecular force b/w then.
Density is a vector quantity
and its unit is kg/m3.
Q.4 Defines pressure?
Pressure:- force per unit area is
called pressure if we have a unit area “A” at which force “F” is acting then
the press “P” is given by/
Pressure = force/area => p = f/A
Its unit is Pascal.
Q.5 Define and explain atmospheric pressure?
Ans. The force excreted by the thick layer of air surrounds earth is called atmospheric pressure
This is a layer of air
around us which is called atmosphere, we live in the ocean of air which exerts a force upon our body and it is equal to 100,000 Pascal which is called one
atmospheric presser.
Q. 6 write a note on barometer?
Ans. Barometer
:- A
devise which is used for measurement of atmospheric pressure is called
barometer consists of a glass filled with mercury one end of the glass is sealed
and the other is dipped in mercury when atmospheric pressure presses the
mercury toward the mercury rises up in glass tube the glass is graduated with
different values the height of mercury in the glass shows the value of atmospheric the pressure at sea level the mercury can rise up to 16cm at 00c and it
is known as the standard of atmospheric pressure.
Q..7 write application of atmospheric
pressure in our daily life?
Ans. Some applications of
atmospheric pressure are given below.
Sucking
throw straw:- when we suck any liquid through a straw the volume of lungs increases
and the air pressure decreases. As a result of the atmospheric rise in straw.
Surfing:- when we draw any liquid
with the help of syring the pressure inside the syringe decreases while the
pressure a surface of liquid increases which forces the liquid ongoing into
syring.
while the pressure a
surface of liquid increases which forces the liquid on going into syring.
Q.8 explains how weather changes with
atmospheric pressure.
Ans. If we keep barometer at the same high above the sea level if will show the changes of the day by day pressure.
These pressure changes are shown on a weather map. These lines which loins all
places at the same atmospheric pressure are called I so bar. The unit which is
used for weather map is called mill bar ( m bar)
100m bar = 1 bar => 1bar
= 100kpa
The atmospheric pressure
usually changes from 1040 bar to as low as 950 bar. The wind moves from high-pressure regions to low-pressure regions. The winds of low-pressure areas move
anti-clockwise while the wind of high-pressure areas move clock-wise in the northern hemisphere. The strength of the wind is determined by the pressure
gradient.
Q.9 state and explain Pascal’s law?
Explanation:- consider a container having
four openings A, B, C and D as shown In figure. There are moveable pistons in
every opening.
Now if we this container
with water or any other liquid. Then we apply some force on anyone piston of
them. Suppose we apply force on “A” as soon as we apply force on piston “A” at
the same time the other three pistons will also start moving outwards. This
experiment shows that pressure exerted on any liquid in any container is
distributed equally in all directions.