:::: MENU ::::
September 07, 2022 | No comments

Solution to Exercise's Conceptual Questions and Long Questions of Chapter 1| Physical quantities and Measurements | Physics Class 9 Notes

 



Conceptual Question Answers

1: How technology is shaped by physics?

Already solved in the short questions section of this blog. 

2: Physics and Biology are considered different branches of science, how Physics links with Biology.

The link between Physics and Biology can be studied in Biophysics.

Biophysics

The study of biological processes using the knowledge and techniques of physics is called biophysics.

The link between Physics and Biology

Physics and Biology are closely related, following are some of their examples

  • Physics explains the effects of temperature, gravity, light, etc. on living things.
  • Physics enables biologists to study tiny particles with powerful microscopes.
  • Physics develops new medical instruments, such as Computer tomography (CT Scan), Magnetic resonance imaging (MRI), Laser surgery, etc.
  • Physics explains the reception of light rays and image formation by the eye.
  • The movement of muscles and bones can be explained by the principles of Physics.
  • In physiology, bioenergetics, neurosciences, pharmacology, etc. Physicists play a key role.

3: Why are measurements important.

Already solved in the short questions section of this blog.

4: Why area is a derived quantity?

The area is a derived quantity of length

The physical quantity that is obtained by multiplying or dividing one base quantity with another base quantity is called derived physical quantity.

We know that,        Area = length x width

So it is clear from the above formula that Area is derived physical quantity, because it is obtained by multiplying the length (base quantity) with width (another base quantity).

5. Name any four derived units and write them as their base units.

Sr #

Name of Derived units

Symbols of Derived units

Name of base units

Symbols of base units

 

1

Volume

V

cubic meter

m3

 

2

Force

F

Newton

N=〖kg ms-2〗

 

3

Pressure

P

Pascal

Pa=〖kgm-1〗s-2

 

4

Work, Energy

W

Joule

J=〖kgm2〗s-2

 

5

Speed, Velocity

v

meter-per-second

〖ms-1〗

 

Note:  The letters given in boldface are the special names given to combinations            of SI units.

 

6. Why in Physics do we need to write in scientific notation.

Need of expressing numbers in scientific notation in Physics

The method of expressing a very large or very small number in the power of 10 is known as standard form or scientific notation.

Explanation

In physics, we mostly deal with either very large or very small numbers. For example, astrophysicists are mostly concerned with large values such as earth-to-sun distance (149,600,000,000 m). Similarly, bio-physicists studying microorganisms are mostly concerned with very small values, such as the mass of bacterial cell (0.000,000,000,005 kg). For using such values in their calculations, scientists mostly express them in scientific notation.

7: What is Least Count? How least counts of Vernier Calliper and Screw Gauge are defined?

Already solved in the short questions section of this blog

8: How can we find the volume of a small pebble with the help of a measuring cylinder?

To find the volume of irregularly shaped bodies (Pebble)

  • Pour water into the cylinder.
  • Note the volume of water as “V1”.
  • Put some irregular shape body (let small pebble) and again note the volume but as “V2”.
  • Now to find the volume of the pebble (V) subtract the volume of water (V1) from the newly taken reading for volume (V2).
  • Mathematically  Volume of pebble = V = V2-V1

Give an extended response to the following questions (Long Question Answers)

1: Define Physics. How does Physics play a crucial role in science, technology, and society? 

Ans     See Q# on Page#

2: What is SI? Name SI base quantities and their units.

Ans     See Q# on Page#

3: What are Physical quantities? Distinguish base and derived physical quantities.

Physical quantities 

Those quantities which are measurable are called Physical quantities.

Explanation

The thickness of our hair, the volume of a liquid, the mass of the earth, the length of a book, etc. are physical quantities because they can be measured. If we write 10, it is a number but if we write 10 kg then it is a physical quantity.

Differences between the base and derived physical quantities

Base physical quantities

Derived physical quantities

Those minimum number of physical quantities and their defined and standardized units in terms of which all other physical quantities can be expressed are called Base physical quantities.

The physical quantities defined in terms of base quantities are called derived physical quantities.

They are seven in numbers.

They are many in numbers.

Units of base physical quantities are standardized and defined.

Units of derived physical quantities are not as standardized and defined as base physical quantities are.

Units of base physical quantities are also unique, so there is no combination of units with each other.

In units of most derived physical quantities, there is no uniqueness and so they are formed by the combination of each other.

Examples:

Length, Mass, Time, Electric current, Temperature, Luminous intensity (intensity of light), and amount of a substance.

Examples:

Volume, Force, Pressure, Work, Energy, Speed, Velocity, Density, etc.

 

4: What is standard form/scientific notation?

Ans     See Q# on Page#

5: What are prefixes? Explain with examples.

Ans     See Q# on Page#

6: Describe the construction and use for measurement of the following instruments.
(a)      Vernier caliper (b)     Screw gauge

Ans     See Q# on Page#

7: What is meant by the significant figures of measurement? What are the main points to be kept in mind while determining the significant figures of a measurement?

Ans     See Q# on Page#
Categories:

0 Comments:

Post a Comment