1.
What
do you mean by physical quantities?
-
Those
quantities which can be measured and can be expressed in terms of some
numerical value are called physical quantities. For example: length, mass, time
etc.
2.
Why
love, sympathy, anger etc are not physical quantities?
-
These
cannot be expressed in terms of some numerical value. So these are not physical
quantities.
3.
What
is measurement?
-
The
comparison of unknown quantities with same standard quantities is known as
measurement.
4.
What is the importance of measurement in our
daily life?
-
Measurement
has very important role in our daily life in the following way:
a.
To
conduct scientific experiments.
b.
To
simplify trade and transactions
c.
Taking
proper medicines.
d.
Cooking
properly.
e.
To
get accurate time.
f.
For
sports.
g.
For
transportation. Etc
5.
Why
we cannot imagine our daily life without measurement?
-
Measurement
is very useful in our various sector of life as scientific study, trade,
medicine, cooking, sports, time, transportations etc. So we cannot imagine our
daily life without measurement.
6.
What
do you mean by fundamental quantities?
-
Those
quantities which are independent of other quantities are fundamental
quantities. For example: length, mass, time etc. ( In another language the
quantities which can neither be formed nor can be divided into other quantities
are called fundamental quantities.)
7.
What
do you mean by derived quantities?
-
Those
quantities which can only be formed with the help of fundamental physical
quantities are known as derived quantities. For example: area, volume, speed
etc.
8.
Differentiate
between fundamental and derived physical quantities.
(Instructions to students: in the
section of differentiate questions, you need to show comparative points not
definitions. And you should not show the points which cannot be compared. For
example if you are showing the difference between you and your friend, then
don’t compare eye and hand, compare eye and eye, hand to hand, foot to foot. I
hope you understood)
(Dear students! the question is
about quantities, so be careful, don’t include units.)
-
The
difference between fundamental and derived physical quantities are as follows:
Fundamental
Physical Quantities
|
Derived
Physical Quantities
|
1. These are independent to other
quantities.
|
1. These are dependent on
fundamental physical quantities.
|
2.
These
are 7 in number.
|
2. These are numerous.
|
3. These can be measured directly.
|
3.
These can’t be measured directly. Parent quantities should be measured
first.
|
4. For example: Length, mass, time
etc.
|
4.
For example: Area, volume, speed etc.
|
9.
What
do you mean by unit of measurement?
-
The
unit of measurement is defined as the definite magnitude of quantity which is
used as a reference for the measurement. For example, unit of length is Meter;
unit of time is Second etc.
10. What do you mean by fundamental
units?
-
Those
units which are independent of other units are called fundamental units. For
example: meter (m), kilogram (Kg), second (s), ampere (A), candela (Cd), mole
(Mol), Kelvin (K).
( In another language fundamental and derived quantities can be defined as given in video)
( In another language fundamental and derived quantities can be defined as given in video)
11. What do you mean by derived
units?
-
Those
units which are dependent on fundamental units are called derived units. For
example: m/s2, m3, kgm-3etc,
12. Differentiate between fundamental
and derived units.
-The
differences between fundamental and derived units are as follows:
Fundamental
Units
|
Derived
Units
|
1. These are independent of other
units.
|
1. These are dependent on
fundamental units.
|
2. These are 7 in numbers.
|
2. These are numerous.
|
3. For example: meter, second,
kilogram, candela, mole, ampere, Kelvin.
|
3. For example: m/s, kg/m3
etc.
|
4. These are the units of
fundamental quantities.
|
4. These are the units of derived
quantities.
|
13. Define MKS (Metric System)
System.
-
The
system of measurement in which length is measured meter, mass is measured in kilogram
and time is measured in second is known as MKS System.
14. Define CGS System.
-
The
system of measurement in which length is measured in centimeter, mass is
measured in gram and time is measured in second is known as CGS System.
15. Define FPS System.
-
The
system of measurement in which length is measured in foot, mass is measured in
pound and time is measured in second is known as FPS System.
16. Why unit of density is called as a
derived unit?
-
The
unit of density (kg/m3) is obtained from two fundamental units: kg
and m. So it is called as a derived unit.
17. Why unit of power is called as a derived
unit?
-
The
unit of power (kgm2/s3) is obtained from three
fundamental units: kg, m and s. So it is called as a derived unit.
(Dear students you
may be asked similar type of questions as pressure, work, momentum, velocity,
acceleration, area etc. which are to be answered like above illustrations.)
18. What is SI System?
-
The
International System of units which is accepted all over the world is known as
SI System. SI system uses seven fundamental units which are meter (m) of
length, kilogram (Kg) of mass, second (s) of time, ampere (A) of current,
candela (Cd) of luminous intensity, mole (Mol) of amount of substance and
Kelvin (K) of temperature.
(Dear students if
this question is as very short type, give only one line answer and if asked as
a long question give all description.)
19. What are the advantages
(benefits) of SI System?
-
Following
are the advantages of SI System:
a.
It
brings uniformity in measurement globally.
b.
It
minimizes discrepancy and false measurement.
c.
It
is rational; it uses only one unit for one physical quantity.
d.
It
is coherent; all derived units can easily be derived.
e.
Multiples
and sub multiples can easily be expressed in terms of power of 10.
20. Why SI system is called as
extended system of MKS system?
-
It
is because SI system includes seven fundamental units meter, kilogram, second,
Kelvin, ampere, candela and mole which includes three fundamental units meter,
kilogram and second. So SI system is called as extended system of MKS system.
21. Measurement scales in the market
should be re-calibrated by government regularly, why?
-
It
is to stop the discrepancy in the measurement and false measurement by traders.
22. What are the differences between
SI and MKS system?
-Following
are the differences between SI and MKS system:
SI
System
|
MKS
System
|
1. It uses 7 fundamental units
|
1. It uses only three fundamental
units.
|
2.
It
covers all needs of measurement in Science, Engineering and Commerce.
|
2. It covers only mechanics and traditional
commerce.
|
( What do you mean by unit? Ans.: Magnitude of measurement is known as unit.)
23. What do you mean by mass? (Questions
onward for class 8)
-
It
is amount of matter contained in a body. It depends on the number of atoms and
its atomic mass.
24. What do you mean by standard mass
of 1Kg?
-
It
is defined as the mass of an international sample of a cylinder made
of platinum-iridium which is kept at the International Bureau of Weights and
Measures.
25. What is gravity?
-
The
force which attracts body towards the centre of the earth is known as gravity.
Unit of gravity is m/s2.
26. What do you mean by weight?
-
The
net force of gravity acting on a body is known as weight.
Unit of weight is
Newton (N). It can be calculated as: W = m x g. (where, w = weight, m = mass
and g = gravity, g = 9.8m/s2)
27. Write down the differences
between mass and weight?
-
The
differences between mass and weight are as follows:
Mass
|
Weight
|
1. It is total amount of matter
contained in a body.
|
1. It is net force of gravity
acting on a body.
|
2.
Mass
of a body remains constant everywhere.
|
2. Weight of a body changes from place to
place.
|
3. It is scalar quantity.
|
3.
It is a vector quantity.
|
4. Unit of mass is Kg.
|
4. Unit of weight is Newton (N).
|
5. It is measured by using pan
balance.
|
5. It is measured by using spring
balance.
|
28. Why does weight of a body changes
from place to place?
-
It
is due to effect of gravity. The place where the acceleration due to gravity is
more, weight of a body becomes more and the place where the acceleration due to
gravity is less, weight of a body becomes less.
29. What do you mean by zenith?
-
The
imaginary point in the sky just above our head when we stand straight is known
as zenith.
30. What is one solar day?
-
The
time taken by the earth to rotate once on its own axis is known as one solar
day.
(In another word
the time taken by the sun to reach again in the same zenith when it moves once
from it is known as one solar day.)
(The time interval
between two successive transits by the sun of the meridian directly opposite
that of the observer is known as one solar day.)
You can write any
one of your choice.
31. What do you mean by 1 second
time?
-
1/86400
part of one solar day is defined as 1 second.
( 1 Solar day = 24 Hrs
= 24 x 60 min
= 24 x 60 x 60 s
= 86400 s )
CONVERSION OF
UNITS
For
conversion of units following points to be remembered:
-
First
identify in which unit we are converting, into
smaller or into larger. For example: 5 km into meter: larger into smaller, 120 seconds into minute: smaller into larger.
-
Find
out the relationship between units means 1 larger unit = how much smaller unit.
1km = 1000m and 1 min = 60s as given in example.
-
Multiply with smaller units to convert into smaller unit. 5km = 5 x 1000m = 5000m.
-
Divide with smaller units to convert into larger unit. 120 seconds = 120/60 min = 2 min.
32. Convert 36 km/hr into m/s. (or
covert 36km/hr into SI unit)
-
36km/hr
= (36x1000)/(60x60) = 36000/3600 = 10m/s
33. Convert 15000kg/m3
into g/cm3.
-
15000kg/m3
= (15000x1000)/(100x100x100) = 15000000/1000000 = 15g/cm3
-
GOOD
LUCK -
Thanks for reading. Please don’t
forget share any suggestions, comments and questions its my humble request.
