9th Physics Important Question and Answers of Chapter 1

 

CHAPTER # 1

PHYSICAL QUANTITIES AND MEASUREMENTS

Important Questions:

Q1: What is the Difference between Physical and Electronic Balance?

Physical balance	Electronic balance
It is used to measure mass by comparison.	It does not require any comparison mass to measure it.
Its least count is 0.01g.	Its least count is 0.001g.
It is more accurate.	It is more precise.

Q2: Difference between precision and accuracy.

Precision	Accuracy
If the least count of any measuring instrument is greater, then it has greater precision.	If the least count of any measuring instrument is lesser, then it has an accuracy.
For Instance; If we measure the diameter of the wire with the help of the vernier caliper as 1.02cm and with the screw gauge as 1.023cm then the screw gauge is precise and the vernier caliper is accurate.

Q3: On what factors does the accuracy in measuring a physical quantity depend?

The accuracy depends on the skill of the observer, the number of observations, and the quality of the measuring instrument.

Q4: Write laboratory safety equipments.

First aid box, sand buckets, water buckets, fire extinguisher, and fire alarm.

Q5: Differentiate mechanical and digital stopwatches.

Mechanical Stopwatch	Digital Stopwatch
·         A mechanical stopwatch is one that is used to measure time intervals of up to 0.1 seconds. ·         It is mostly used for sports purposes. ·         It operates with a single knob.	·         A digital stopwatch is one that can measure time intervals as short as 0.01 seconds. ·         It is mostly used in laboratories. ·         It operates with buttons.

Q6: What is the pitch of the screw gauge?

The pitch of the screw gauge is the distance between consecutive threads on the main scale index line. For example, if the distance is 1mm, the pitch is also 1mm.

Q7: Which telescope provides information about stars?

The Hubble space telescope provides information about stars and it orbits around earth.

Q8: Write at least five multiples or sub-multiples of length.

Kilometer (km), decimeter (dm), centimeter (cm), millimeter (mm), micrometer (ƞm).

Q9: Write the SI units of length, area, and volume.

Quantity	SI unit
Length	Meter (m)
Area	Meter square (m2)
Volume	Meter cube (m3)

Q10: 1m³ (cubic meter) is equal to how many litres?

1m³ (cubic meter) is equal to 1000 litres.

Q11: What is a unit?

A standard is set to expressed quantities. This standard is known as the unit of that quantity. For instance; a unit of mass is the kilogram (kg).

Q12: Differentiate physical and biological sciences.

Physical Sciences	Biological Sciences
The term “physical science” refers to a branch of science that focuses on the study of nonliving things. For instance, chemistry, physics, etc.	The term "biological sciences" refers to a branch of science that focuses on the study of living things. Take zoology, botany, etc. as examples.

Chapter # 1 Exercise

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