Question

....S.
1. What is meant by measurement ?
2. What do you understand by the term unit ?
5. What are the three requirements for selecting a unit
of a physical quantity ?
1. Name the three fundamental quantities.
5. Name the three systems of unit and state the various
fundamental units in them.
5. Define a fundamental unit.
7. What are the fundamental units in S.I. system ? Name
them along with their symbols.
3. Explain the meaning of derived unit with the help of
one example.
2. Define standard metre.
1. Name two units of length which are bigger than a
metre. How are they related to the metre?
1. Write the names of two units of length smaller than a
metre. Express their relationship with metre.
2. How is nanometre related to Angstrom ?
3. Name the three convenient units used to measure
length ranging from very short to very long value.
How are they related to the S.I. unit ?
4. Name the S.I. unit of mass and define it.
5. Complete the following:
(a) 1 light year =
.m
(b) 1 m
А
(c) 1 m
u
(d) 1 micron
А
(e) 1 fermi
Ans. (a) 9-46 x 1015 (b) 1010 (c) 10 (d) 104 (e) 10-15
5. State two units of mass smaller than a kilogram. How
are they related to kilogram?
7. State two units of mass bigger than a kilogram. Give
their relationship with the kilogram.
18. Complete the following:
(a) lg
kg
(b) 1 mg
kg
(c) 1 quintal
kg
(d) 1 a.m.u (or u)
..... kg
Ans. (a) 10-3 (b) 106 (c) 100 (d) 166 x 10-27
19. Name the S.I. unit of time and define it.
20. Name two units of time bigger than a second. How
are they related to second ?
21. What is a leap year?
22. “The year 2020 will have February of 29 days'. Is this
statement true ?
Ans. Yes
23. What is a lunar month?
24. Complete the following:
(a) 1 nano second
....S.
(b) 1 us
(c) 1 mean solar day = ....S.
(d) 1 year
Ans.(a) 10-9 (6) 106 (c) 86400 (d) 3-15x107
25. Name the physical quantities which are measured in
the following units :
(a) u
(b) ly
(c) ns (d) nm
Ans.(a) mass (b) distance (or length) (c) time (d) length
26. Write the derived units of the following:
(a) speed
(b) force
(c) work
(d) pressure
Ans.(a) m s-1 (b) kg m s? (c) kg m² 52 (d) kg m-'s-2
27. How are the following derived units related to the
fundamental units ?
(a) newton
(b) watt
(c) joule
(d) pascal.
Ans.(a) kg m s? (b) kg m?s(c) kg m? s? (d) kg m-'s
..S.
m
9​

Answer 1

1. Measurement is the numerical quantification of the attributes of an object or event, which can be used to compare with other objects or events. ...
2. Unit is the quantity of a constant magnitude which is used to measure the magnitudes of other quantities of the same nature.
3. (1) It should be possible to define the unit without ambiguity. (2) The unit should be reproducible. (3) The value of units should not change with space and time.
4. The choice of which physical quantities are taken as fundamental is somewhat arbitrary, but the three usually selected are length, time, and mass