Chapter
1: Physical Quantities and Measurements
Q/A From
The Text Book (PTBB)
Q1: What is the difference between base
quantities and derived quantities? Give three examples in each case.
Ans:
|
Base Quantities
|
Derived Quantities
|
|
Base quantities are the quantities on the
basis of which all other quantities are expressed.
Examples:
Length, mass, time, electric current,
temperature, intensity of light and amount of substance.
|
Derived quantities are the quantities which
are expressed in terms of Base quantities.
Examples:
Volume, speed, force, work, energy, power
and charge.
|
Q2: Pick out
the base units from the following:
Joule,
Newton, killogramme, hertz, mole, ampere, metre, Kelvin, coulomb and watt.
Ans: Kilogram, mole, ampere, metre and Kelvin are the base units.
Q3: Find the
base quantities involved in each of the following derived quantities:
(a) speed (b)
volume
(c) force (d)
work
Ans: (a) Speed:
Derived from “length and time”
(b)
Volume:
Derived from “length”
(c)
Force:
Derived from “Kilogram, length and time”
(d)
Work:
Derived from “Mass, length and time”
Q4: Estimate
your age in seconds.
Ans: My age in thirteen years. Its value in seconds is
13 years = 13 x 365 x 24 x 60 = Seconds.
Q5: What
role SI units have played in the development of science?
Ans: SI units have played a very important role in the development of
science. SI units are very helpful to exchange scientific and technical
information at the international level.
Q6: What is
meant by Vernier Constant?
Ans: Least Count Of Vernier Calipers is called Vernier Constant.
Q7: What do
you understand by the zero error of a measuring instrument?
Ans: When zero Of moveable Scale does not coincide with main scale, then
instrument has “Zero Error”.
Q8: Why is
the correction of Zero Error necessary in a measuring instrument?
Ans: Correction of Zero Error is necessary in measuring instrument to
obtain an extreme correct value.
Q9: What is
a stopwatch? What is the least count of a mechanical stopwatch you have used in
the laboratories?
Ans: Stopwatch is a device which is used to measure a time interval
of an event. Mechanical stopwatches have least count upto 0.1 seconds.
Q10: Why do
we need to measure extremely small intervals of time?
Ans: In nature and also in Physics, there are so many phenomenon
which vary with respect to the extremely small interval of time and for their
experimental measurement we need very precise time measuring instrument. We
need to measure extremely small interval of times to calculate the time
interval of natural and artificial events.
Q11: What is
meant by Significant Figures of a measurement?
Ans: All the accurately known digits and the first doubtful digit in
an expression are called significant figures. Significant figures reflect the
precision of a measured value of a physical quantity.
Q12: How is
precision related to the significant figures in a measured quantity?
Ans: An improvement in the
quality of measurement by using better instrument increases the significant
figures in the measured results. The significant figures are all the digits are
known accurately and the one estimated digit.
20 February 2017 at 21:05
It is a very helpful website for students