Matric Notes Physics 9th Ch 1 Physical Quantities & Measurements Short Questions

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Conceptual Questions

Q.1) How technology is shaped by physics?

Answer: Physics and technology are closely related however they are also different from each other. Physics is concerned with gathering knowledge and organizing it. Technology lets us use that knowledge for practical purposes.

Behind every technology a physical phenomenon exists, Physics has played its part in the process of humankind and in the improvement of the quality of living.

Q.2) Physics and biology are considered different branches of science, how physics links with biology?

Answer: Physics has provided a basic understanding of the development of new instruments. In biology, we have developed CT scan machines, MRI and laser surgeries. These technologies work on the principle of Physics i.e. resonance, magnetism and optics respectively.

Q.3) Why are measurements important?

Answer: Measurement is a comparison between an unknown quantity and a standard to see how many times as big it is.

Measurement is important because it let the scientist perform the experiments or form theories. It’s not only important in science but in various fields.

Q.4) Why area is called a derived quantity ?

Answer: Generally, a derived physical quantity is a combination of more than one base physical quantities. The area is a derived physical quantity because a basic quantity (length) is occurring two times.

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

Q.6) Why in Physics we need to write in scientific notation?

Answer: The need to write in scientific notation is that it is an internationally accepted way of writing numbers. With the help of it, we can write very large or very small numbers in the power of 10 with only one non zero digit before the decimal.

Q.7) What is least count? How least count for vernier calliper and screw gauge are defined?

Answer: The smallest value that can be measured accurately by an instrument is called its least count.

Least count for Vernier Calliper.

If the smallest main scale division is 1 mm and vernier scale has 10 division on it then the least count is

Least count = 1 mm/ 10 = 0.1 mm

Least count for Screw Gauge:

If the pitch of the screw gauge is 0.5 mm and the number of divisions on the circular scale is 50 then

Least count = 0.5 mm/ 50 = 0.01 mm

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

Answer: We can find the volume of a small pebble with the help of measuring cylinder in the following steps

1. In the first step, put some liquid in the measuring cylinder more than the height of the pebble.

2. Now measure the level of the liquid and call it ‘V1‘.

3. In the next step, add the pebble into the cylinder and measure the level of the liquid again.

4. Now measure the level of the liquid and call it “V2.”

5. The difference between the two levels will give the volume of the pebble

∆V= V2 – V1.

Q.9 Define measurement, unit, and magnitude?

Answer: Measurement:-the comparison of an unknown quantity with some standard is called measurement.

Unit:-the standard with which things are compared is called unit-meter, kg, second.

Magnitude:- A number with a proper unit is called magnitude. eg 3kg is magnitude.