- (a) mm < cm < m < km
- (b) mm > cm > m > km
- (c) km < m < cm < mm
- (d) mm > m > cm > km
Answer:
(a) mm < cm < m < km
- (a) mass
- (b) weight
- (c) time
- (d) length
Answer:
(d) length
- (a) 100 quintals
- (b) 10 quintals
- (c) 1/10 quintals
- (d) 1/100 quintals
Answer:
(b) 10 quintals
- (a) Spring balance
- (b) Beam balance
- (c) Physical balance
- (d) Digital balance
Answer:
(a) Spring balance
- Metre is the unit of length.
- 1 kg of rice is weighed by beam balance.
- Thickness of a cricket ball is measured by vernier caliper.
- Radius of a thin wire is measured by screw gauge.
- A physical balance measures small differences in mass up to 1 mg or less.
If false, correct the statement.
Answer: False
Correct Statement:
The SI unit of electric current is ampere.
Answer: True
Answer: True
Answer: True
Answer: True
Answer: True
| Quantity | Unit |
|---|---|
| Length | metre |
| Mass | kilogram |
| Time | second |
| Temperature | kelvin |
| Instrument | Used For |
|---|---|
| Screw gauge | Coins |
| Vernier caliper | Cricket ball |
| Beam balance | Vegetables |
| Digital balance | Gold ornaments |
Choose the correct answer:
- (a) Both A and R are true but R is not the correct reason.
- (b) Both A and R are true and R is the correct reason.
- (c) A is true but R is false.
- (d) A is false but R is true.
Assertion (A):
The scientifically correct expression is “The mass of the bag is 10 kg”.
Reason (R):
In everyday life, we use the term weight instead of mass.
Answer:
(a) Both A and R are true but R is not the correct reason.
Assertion (A):
0°C = 273.15 K. For convenience, it is rounded off to 273 K.
Reason (R):
To convert Celsius temperature into Kelvin, we add 273 to the given temperature.
Answer:
(b) Both A and R are true and R is the correct reason.
Assertion (A):
Distance between two celestial bodies is measured in terms of light year.
Reason (R):
The distance travelled by light in one year is one light year.
Answer:
(b) Both A and R are true and R is the correct reason.
Correction made:
The original answer marked as option (d) was incorrect.
A light year is indeed used to measure large astronomical distances.
Answer:
Measurement is the process of comparing a given physical quantity with a known standard quantity of the same nature.
Answer:
A unit is a quantity of constant magnitude used to measure other quantities of the same nature.
Answer:
International System of Units.
Answer:
The least count of an instrument is the smallest measurement that can be measured accurately using that instrument.
Formulae:
For Vernier Caliper:
For Screw Gauge:
Answer:
Pitch of a screw gauge is the distance moved by the screw in one complete rotation.
Answer:
No. A ruler is not accurate enough to measure the diameter of a thin wire. A screw gauge is used instead.
Answer:
- Units named after scientists are written in lowercase letters.
Example: joule, kelvin, newton
- Symbols are generally written in lowercase.
Example: m, kg, s
- Symbols derived from scientists’ names are written in capital letters.
Example: N, J, C
- Symbols are not followed by a full stop.
Example: 75 cm
- Symbols are never written in plural form.
Example: 100 kg (not 100 kgs)
Answer:
Standard units are needed to maintain uniformity and accuracy in measurements throughout the world.
| Mass | Weight |
|---|---|
| Fundamental quantity | Derived quantity |
| Scalar quantity | Vector quantity |
| Amount of matter in a body | Gravitational force acting on a body |
| Constant everywhere | Varies from place to place |
| Measured using physical balance | Measured using spring balance |
| SI unit: kilogram (kg) | SI unit: newton (N) |
Answer:
It is the minimum value measured accurately using a vernier caliper.
Answer:
Procedure:
- Determine the pitch and least count of the screw gauge.
- Place the tea cup between the studs.
- Rotate the ratchet until the cup is held gently.
- Note the pitch scale reading (PSR).
- Note the head scale coincidence (HSC).
- Calculate thickness using:
- Repeat readings at different positions and calculate the average.
Answer:
Procedure:
- Determine the pitch and least count of the screw gauge.
- Place the coin between the studs.
- Rotate the ratchet gently.
- Note PSR and HSC.
- Calculate thickness using:
- Repeat readings and calculate the average value.
Question:
Inian says one light year is (9.46 \times 10^{15}) m.
Ezhilan says it is (9.46 \times 10^{12}) km.
Who is correct?
Solution:
Both are correct because:
Given:
- MSR = 7 cm
- VC = 6
- LC = 0.01 cm
Diameter:
Radius:
Correction made:
Original answer incorrectly converted units to metres.
Given:
- PSR = 1 mm
- HSC = 68
- LC = 0.01 mm
Calculation:
Given:
Using:
Using Vernier Caliper to Find the Outer Diameter of a Pen Cap
Aim:
To find the outer diameter of a pen cap.
Materials Required:
- Vernier caliper
- Pen cap
Result:
The outer diameter of the pen cap = 9.35 cm
Possible textbook typo noted:
A pen cap diameter is usually around 0.935 cm or 9.35 mm.
Determining Thickness of a Single Sheet Using Screw Gauge
Result:
The thickness of a single sheet = 0.30 mm
Given:
Using:
Given:
40 apples = 5 kg = 5000 g
(i) Mass of 12 apples
(ii) Mass of one apple
Answer:
Mass of one apple = 125 g
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