9th Class Chapter 1 Physics Long Questions

Write a note on Waves as carriers of Energy?

Waves as carriers of Energy: Energy can be transferred from one place to another through waves. Example: When we shake the stretched string up and down, we provide our muscular energy to the string. As a result, a set of wave can be seen travelling across the string. The vibrating force from the hand disturbs the particles of string and sets them in motion. These particles then transfer their energy to the adjacent particles in the string. Energy is thus transferred from one place of the medium to other. Dependence: The amount of energy carried by the wave depends on the distance of the stretched string from its rest position. That is the energy in a wave depends on the wave amplitude of wave. If amplitude and frequency are greater than more energy will be transfer. Example: If we shake the string faster, we give more energy per second to produce wave of higher frequency, and wave delivers more energy per second to the particles of the string as it moves forward. Energy. Transfer in Water: Water waves also transfer energy from one place to another. Example: If we drop a stone into pond of water. Water waves will be produce on the surface of water and will travel outward. Now if we place a cork at some distance from the falling stone. When waves reacts the cork, it will move up and down along with the motion of the water particles by getting energy from the wave. This shows that water waves like other waves transfer energy from one place to another without transferring in matter.

Define physics and explain its branches.

Physics: Physics is a branch of science that deals with matter, energy and their relationship. Branches of Physics: Following ate branches of physics: 1- Machanics: It is the study of motion of objects, its causes and effects. 2- Heat: It deals with the nature of heat , modes of transfer and effects of heat 3- Sound: It deals with the physical aspects of sound waves , their production, properties and applications. 4- Light : It is the study of the physical aspects of light, its properties, working and use of optical instruments. 5- Electricity and Magnetism: It is the study of the charges at rest and in motion their effects and their relationship with magnetism. 6- Atomic Physics: it is the study of the structure and properties of atom 7- Nuclear Physics: It deals with the properties and behavior of nuclei and the particle within the nuclei: 8- Plasma Physics: It is the study of production, properties of the ionic state of matter 9- GeoPhysics It is the study of the internal structure of the Earth.

A Chocolate wrapper is 6.7 cm long and 5.4cm wide. Calculate its area upto reasonable number of significant figures.

Given Data: Length = 6.7cm Width = 5.4cm Area = ? Solution: Area = length x width putting the values = 6.7 x 5.4 = 36.18cm² = 36.2 cm²

Define Physical quantities. Also write its types.

Physical Quantities: All measurable quantities are called physical quantities such temperature. A physical quantity possesses at least two characteristics in common. One is its numerical magnitude and the other is the unit in which it is measured. Example: If the length of a student is 104 cm then 104 is its numerical magnitude and centimeter is the unit of measurement. Types of Physical Quantities: Physical quantities are divided into base quantities and derived quantities 1- Base Quantities: There are seven physical quantities which form the foundation for other physical quantities, These physical quantities are called the base quantities. These are length, mass, time, electric current. Temperature, intensity of light and the amount of a substance. 2- Derived Quantities: Those physical quantities which are expressed in terms of base quantities are called the derived quantities. These include area, volume. speed, force, work, electric charge, electric potential etc.

What are the significant figures in the following measurements?

1- 1.66 x10^-27kg =1.66/10^27 kg = 1.66/100000000000000000000000000 kg =0.0000000000000000000000000166 kg Significant figures =3 2- 2001s Significant =4 3- 1.009m Significant =4

What is meant by Vernier callipers? Write its construction.

Vernier Callipers: A vernier callipers consist of two jaws. One is a fixed jaw with main scale attached to it. Main scale has centimeter and millimeter marks on it the other jaw is a moveable jaw, it has a vernier scale having 10 divisions over it such that each of its divisions is 0.9mm.The difference between one small division on main scale division and one vernier scale division is 0.1mm. It is called least count of the vernier callipers. Least count of =Smallest reading on main scale /no. Of decision on vernier scale Vernier Callipers LC = 1mm/10divisions = 0.1mm LC = 0.1mm = 0.01cm Zero Error and Zero Correction: First of all find the zero error. To find the zero error close the jaws of Vernie, callipers gently.Zero error will exist if zero line of the vernier scale is not coinciding with the zero of main scale Knowing the zero error , necessary correction can be made to find the correct measurement is called zero correction. Taking a Reading on Vernier Callipers: Find the diameter of a solid cylinder using vernier Callipers.Close the jaws till they press the opposite sides of the object gently. Note the complete divisions of main scale past the vernier scale zero in a tabular form. Next find the vernier scale division that is coinciding with any division on the main scale. multiply it by least count of vernier Callipers and add it in the main scale reading. This is equal to the diameter of the solid cylinder. Add zero correction (Z.C) to get correct measurement Repeat the above procedure and record at least three observations with the solid cylinder displaced or rotated each time

Your hair grow at the rate of 1mm per day . Find their growth rate in nms^-1

Solution: Rate of growth = 1mm per day =1mm/day =1x10^-3m/24x60x60s = 0.0000000115ms^-1 = 11.57 x10^-9 ms^-1 = 11.57 nms^-1

Define science and describe how science was divided into various branches

Science :The knowledge gained through observations and experiments is called science .The wor science is derived from the Latin word "scientia", which means knowledge. Science was divided into various branches initially as described below;

Define physics and explain its branches

Physics: the branch of science which deals with the study of matter, energy and their mututal relationship is called physics

What is the importance of physics in our daily life<div><br></div>

Law and principle of physics help us to understand nature

Define physical quantities and explain its types

Physical quantities: All measurable quantities are called physical quantities

Define unit and what is international system of units

Unit: A standard quantity needed for measuring unknown quantities is called unit.

What are prefixes, explain it with examples

Prefixes; The words or letters added before a unit and stand for multiples or sub multiples of that unit are known as prefixes

Define scientific notation. describe it with examples

Scientific Notation; In scientific notation a number is expressed as some power of ten multiplied by a number between 1 and 10. A simple but scientific way to write large or small numbers is to express them in some power of ten.

What are measuring instruments, write the name of some length measuring instruments

Measuring instruments; Measuring instruments are used to measure various physical quantities such as length, mass time , volume etc. measuring instruments used in the past for example sundial, water cock and other time measuring devices used around 1300 AD were quite crude/ on the other hand, digital clocks and watches used now a day are highly reliable and accurate

Explain the construction and use of meter rule and measuring tape.

Meter Rule: meter rule is a length measuring instrument and is commonly used in laboratories to measure length of an object or distance between two points

Give construction and use of vernier calipers

Definition: an accuracy greater than 1mm can be obtained by using instruments such as vernier caliper s.

Describe the working of vernier caliper

Zero Error: The defect present in any instrument is called its zero error. TO find zero error, close the jaws of vernier caliper gently. If zero line of the vernier scale coincides with the zero of the main scale then zero error is zero.

What is screw gauge. How a screw gauge is used to measure diameter of thin wire

Definition: An instrument which can measure length correct up to 0.01 mm or 0.001 cm is called a screw gauge

Write a note on mass measuring instruments

Introduction: Pots were used to measure grain in various part of the world in the ancient time . However, balances were also in use by Greeks and Romans.

What is the most accurate balance . Explain with examples

The mass of one rupee con is done using different balances as given below

write a note on stopwatch and its types

Definition: A stopwatch is used to measure the time interval of an event

What is measuring cylinder. Explain it

Measuring cylinder: A measuring cylinder is a graduated glass cylinder used to measure the volume of liquid and also to fine the volume of an irregular shaped solid object

Write note on significant figure

Significant figure: All the accurately known digits and the first doubtful digit in as expression are called significant figures. It reflects the precision of measure value of a physical quantity