9th Class Physics Chapter 1 Constructed response questions

9th Class Physics Chapter 1 Constructed response questions

1.1 In which unit will you express each of the following.

(a) Thickness of a five-rupee coin:

Millimetres

(b) Length of a book:

Centimetres

(c)  Length of football field:

Meters

(d) The distance between two cities:

Kilometres

(e) Mass of five rupee-coin:

Grams

(f) Mass of your school bag:

Kilograms

(g) Duration of your class period:

Minutes

(h) Volume of petrol filled in the tank of a car:

Litres

(i) Time to boil one litre milk:

Minutes

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1.2 Why might a standard system of measurement be helpful to a tailor?

A standard system of measurement is helpful for a tailor because he can communicate easily and can also ensure accuracy in measurements.

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1.3 The minimum main scale reading of a micrometre screw gauge is 1 mm and there are 100 divisions on the circular scale. When thimble is rotated once, 1 mm is its measurement on the main scale. What is the least count of the instrument? The reading for thickness of a steel rod shown in the figure. What is the thickness of the rod?

Least count of micrometre screw gauge is 0.01 mm or 0.001 cm.

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1.4 You are provided a metre scale and a bundle of pencils; how can the diameter of a pencil be measured using the metre scale with the same precision as that of Vernier Callipers? Describe briefly.

A meter scale is far less precise than Vernier Callipers. Arrange the pencils side by side so they can touch each other very closely without any gap. We will use meter scale to measure the total width of that bundle of pencils. After dividing the total width of that bundle with the number of pencils, we will find the diameter of one pencil precisely.

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1.5 The end of a metre scale is worn out. Where will you place a pencil to find the length?

We will avoid the worn out mark and place the pencil at any clear mark. We will read the scale at the outer end and subtract the starting reading to get the true length.

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1.6 Why is it better to place the object close to the metre scale?

It is better to place the object close to the meter scale to read the marking correctly. This will reduce the chance of error.

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1.7 Why a standard unit is needed to measure a quantity correctly?

A standard unit will ensure accurate, uniform and universally understood measurement.

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1.8 Suggest some natural phenomena that could serve as a reasonably accurate time standard.

There are some natural phenomena that can serve as a reasonably accurate time standard.

sunrise

sunset

phases of moon

Earth’s rotation and revolution

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1.9 It is difficult to locate the meniscus in a wider vessel. Why?

It is difficult to locate the meniscus ( curved surface of liquid inside a container ) in a wider vessel because the liquid surface becomes flat. It makes the meniscus less curved and hard to see.

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1.10 Which instrument can be used to measure:

(i) internal diameter of a test tube

(ii) depth of a beaker?

We will use Vernier callipers to measure internal diameter of a test tube and depth of a beaker.

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Some important links are given below

9th Class Physics New Book 2025 Punjab Youtube

Home Page Notespunjab.com