Physical Quantities and Measurements

9th Class Physics Chapter 1 Exercise Short Questions with Answers

Q#1.2 : What is difference between base quantities and derived quantities . Give three examples in each case .

Q#1.3 : Pick out the base units in the following :

joule , newton , kilogramme , hertz , mole , ampere , metre , kelvin ,coulomb and watt .

Base Units :

Following are base unite :

Kilogram
Metre
Mole
Ampere
Kelvin

Q#1.4 : Find the base quantities involved in each of the following derived quantities :

(a) speed :

Derived from “Length and Time ”
ms^-1

(b) volume :

Derived from “Length” .
m³

(c) force :

Derived from “Mass , Length and Time “.
kgms^-2

(d) work :

Derived from “Mass , Length and Time “.
kgms^-1

Q#1.5 : Estimate your age in seconds .

1 year =	365 days
1 day =	24 hours
1 hour =	60 minutes
1 minute =	60 second

Total seconds in one year = ( 365 × 24 × 60 ×60 )

= 31536000 sec

Suppose , your age is 17 years . So

Total seconds in 17 years = (31536000) × 17

= 536112000 sec

Q#1.6 : What role SI units have played in the development of science ?

SI units have played very important role in the development of science and technology .
Particularly this system is very useful to exchange the scientific and technical information.

Q#1.7 : What is meant by Vernier constant ?

Vernier Constant :

” It is ratio between smallest reading on main scale to the total divisions on Vernier scale .”

or

” The difference between one small division on main scale and one Vernier scale division .”

The least count of Vernier caliper is called Vernier Constant .
Least Count of Vernier caliper is 0.1 mm.

Q#1.8 : What do you understand by the zero error of a measuring instrument ?

Zero Error :

” If the zero of both the scales of a given instrument do not coincide with each other , it means the given instrument has zero error .”

or

” Any fault in the measuring instrument is called zero error of that instrument .”

Example :

Zero error of Vernier Caliper .
Zero error of Screw Gauge .

Q#1.9 : Why is the use of zero error necessary in a measuring instrument ?

It it necessary to find Zero Error of an instrument and apply Zero Correction .

Reason :

To get accurate measurement .
To obtain an extreme correct value .

Q#1.10 : What is stopwatch ? What is the least count of a mechanical stopwatch you have used in the laboratories ?

” A device used to measure the time interval of an event .”

Least Count of Mechanical Stop-watch :

Mechanical stopwatches have least count upto 0.1 second .

Q#1.12 : What is meant by significant figures of a measurement ?

Significant Measurements :

” All the accurately known digits and the first doubtful digit in an expression are called significant figures .“

Example :

0.004080 has 4 significant figures.

Q#1.13 : How is precision related to the significant figures in a measured quantity?

An improvement in the quality of measurement by using better instrument increases the significant figures in the measured results .
The significant figures are accurately known digits and the first doubtful digit in an expression .
→ More number of significant figures → Measuring instrument has smaller value of its least count → Smaller the Least Count larger is the value of precision .

9th chemistry chapter 1 solved exercise short questions

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Short Questions of Punjab Board , Last Five Year ,

Q : What is Physics ?

Physics :

” The branch of science which deals with the study of matter and energy and relation between them .”

Q: Differentiate between Nuclear Physics and Atomic Physics .

Nuclear Physics	Atomic Physics
It deals with the properties and behavior of nuclei and particles with nuclei .	It deals with the study of structure and properties of atom .

Q : What is Electromagnetism ?

” The branch of physics which deals with the study of charges at rest and in motion , their effect and relation with magnetism is called electromagnetism .”

Q : Write two advantages of physics in our daily life ?

A car is made on the principles of mechanics and refrigerator is based on the principle of thermodynamics .
We use mobile phones which are based on principles of physics

Q : Define Physical Quantities ?

Q: What is meant by unit ?

Q: Define SI units ?

Q: Difference between base units and derived units ?

Q : What is term prefix ?

Q: Define Scientific notation ?

Q: What are measuring Instruments ?

Q : What is least count ?

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