Physics Chapter 1|9th Class Short Question||tutoronlines

Chapter# 1

Physical Quantities and Measurement
( Chapter within short Questions)

 

Table of content:

Number of topics Name the topics
1 Physics
2 Branches of physics
3 Vector
4 Scaler
5 Calliper
Q.1 Why do we study physics?

Ans. We study physics because Laws and principle of physics help us to understand the nature. Most of the technologies of our modern society throughout the world are related to physics.

Q.2 Name any five branches of physics?

Ans. (i) Mechanic (ii) Heat (iii) Sound (iv) Light (v) Atomic Physics

Q.3 How can you differentiate between base and derived quantities?
Ans.
Base Quantities:

The quantities on the basis of which other quantities are expressed are called base quantities. Example. Length, time, mass, temperature, electric current, intensity of light, amount of substance.

Derived Quantities:

All the quantities, which can be described in terms of base quantities, are known as derived quantities. Example. Force, area, volume, pressure, speed, velocity, charge density etc.

Q.4 Identify the following as base or derived quantities?

Ans. Density, force, mass, speed, time, length, temperature and volume.
Base Quantities Derived Quantities
Mass, length, time, temperature. Density, force, speed, volume.

Q.5 Name five prefixes most commonly used?

Ans. (i) Kilo (k)=103

(ii) Mega (M)=106

(iii) Centi (c)=10-2

(iv) Milli (m) =10-3

(v) Nano (n) =10-9

Q.6 The sun is hundred and fifty million kilometers away from the Earth. Write this?

Ans. (a) As an ordinary whole number.
150,000,000 km= 150,000,000,000 m
(b) In scientific notation
1•5×1011m

Q.7: Write the numbers given below in scientific notation?

Ans. (a) 3000000000 mS-1

3×10⁹ mS-1

(b) 6400000 m
6•4×10⁶ m
(c) 0•0000548 s
5•48×10-5

Q.8 what is the least count of Vernier callipers?

Ans. Least count of Vernier callipers is 0.1mm or 0.01cm…define as, difference between one small division on main scale and one Vernier scale division is 0.1mm called least count of Vernier callipers.

Q.9 How many divisions are there on its Vernier scale?

Ans. There are 10 division on Vernier scale.

Q.10 Why do we use zero correction?

Ans. Zero correction is used to take correct measurement.

Q.11 What is the least count of a screw gauge?

Ans. The least count of screw gauge is 0.01mm or 0.001cm.

Q.12 What is the pitch of your laboratory screw gauge?

Ans. The pitch of laboratory screw gauge is 1 mm.

Q.13 What is the range of the two instruments which is more precious and why?

Ans. (a) Vernier callipers callipers have range 0.1mm
(b) Screw gauge have range 0.01mm
Screw gauge is more precious because it can measure accurately up to 0.01mm while Vernier calliper can only measure accurately up to 0.1mm

Q.14 What is the function of balancing screws in physical balance?

Ans. Function of the balancing screws is to balance the panes of the physical balance.

Q.15 On what pan we place the object and why?

Ans. We place the object in left pane because standard masses are placed on the right pan.

Exercise Question

Q.1 What is difference between base quantities and derived Quantities? Give three examples in each case?

Ans.

Base Quantities:

The quantities on the basis of which other quantities are expressed are called base quantities. Example. Length, time, mass, temperature, electric current, intensity of light, amount of substance.

Derived Quantities:

All the quantities, which can be described in terms of base quantities, are known as derived quantities. Example. Force, area, volume, pressure, speed, velocity, charge density etc.

Q.2 Pick out the base units in the following: joule, newton, kilogram, hertz, mole, ampere, meter, kelvin, coulomb and watt?

Ans. Base Units
Kilogram (unit of mass)
Mole ( unit of amount of substance in term of numbers)
Ampere (unit of electric current)
Meter (unit of length)
Kelvin ( unit of temperature)

Q.3 Find the base quantities involved in each of the following derived quantities speed, Volume, Force, Work?
Ans. Volume.

Volume= Length x breadth x Height
So Base Quantities in volume involved in length
Unit of volume= m x m x m=m³

Speed:

Speed= Distance/Time
So in speed base quantities involved are length (distance) and time.

Force:

Force= ma
Force= mass x acceleration
F= mass x velocity/time
F= mass x displacement/time×1/time
So in formula of force base quantities are mass of objects, length ( displacement) and time
Unit of work= kgmS-2 x m
Unit of work= joule

Q.4 Estimate your age in second?

Ans. My age is 15 years
days= 15×365=5475 days
 hours= 5475×24=131400 hours
minutes=131400×60=7884000 minutes
second=7884000×60=473040000 second=4.73×10⁸ second.

Q.5 What role SI units have played in the development of science?

Ans. With the developments in the field of science and technology, the need for a commonly acceptable system of units was seriously felt all over the world particularly to exchange scientific and technical information.

Q.6 What meant by Vernier constant?

Ans. The difference between one small division on main scale and one Vernier scale division is 0.01mm called least count of Vernier callipers. Least count of Vernier callipers also called Vernier constant.

Q.7 What do you understand by the zero error of a measuring instrument?

Ans. Any error in Measuring Instruments that can effect the reading is called is called zero error of that instrument.

Q.8 Why is the use of zero error necessary in a measuring instrument?

Ans. The use of zero error is necessary in measuring instrument to take correct measurements.

Q.9 What is a stopwatch? What is the least count of a mechanical stopwatch you have used in the laboratories?

Ans. It is an instrument use to measure the time interval or specific period of an event is known as stop watch. A mechanical stop watch used in laboratories can measure a time, interval up to minimum 0.1 second.

Q.10 Why do we need to measure extremely small interval of time?

Ans. To get the accurate measurement we need to measure extremely small interval of time. Instantaneous time rate of change of variable is calculated with the help of small interval of time.

Q.11 What is meant by significant figures of a measurement?

Ans. In any measurement, the all accurately know digits and first doubtful digit is known as significant figures.

Q.12 How is precision related to the significant figures in measured quantity?

Ans. More significant figures means greater precision. Improvement in the quality of measurement by using better instrument increase the significant figures in the measured result.

Leave a Comment

Your email address will not be published. Required fields are marked *