Mechanics (Physics) (Part-1)

Total Questions: 50

11. The base SI unit of the amount of substance is represented by: [S.S.C. JE Electrical Exam 28.10.2020 (Shift-I)]

Correct Answer: (d) mol
Solution:The fundamental unit of quantity of a substance is the mole.

One mole is equal to approximately 6.022 x 10²³ units (atoms, molecules, ions, etc.) of a substance, a number known as Avogadro's number.

The mass is grams of one mole of substances is equal to the mass number in AMU (Atomic Mass Unit) of one atom/molecule of that substance.

12. Which of the following is the SI unit for the measuring the amount of a substance? [S.S.C. Online CGL (T-I) 18.08.2021 (Shift-II)]

Correct Answer: (a) mole (mol)
Solution:The fundamental unit of quantity of a substance is the mole.

One mole is equal to approximately 6.022 x 10²³ units (atoms, molecules, ions, etc.) of a substance, a number known as Avogadro's number.

The mass is grams of one mole of substances is equal to the mass number in AMU (Atomic Mass Unit) of one atom/molecule of that substance.

13. Which of the following units is used for the measurement of concentration (of the amount of a substance)? [S.S.C. JE Electrical Exam 24.03.2021 (Shift-II)]

Correct Answer: (b) Mole
Solution:The fundamental unit of quantity of a substance is the mole.

One mole is equal to approximately 6.022 x 10²³ units (atoms, molecules, ions, etc.) of a substance, a number known as Avogadro's number.

The mass is grams of one mole of substances is equal to the mass number in AMU (Atomic Mass Unit) of one atom/molecule of that substance.

14. Which of the following combinations of measures of quantity and unit is not a correct match? [S.S.C. Online CHSL (T-I) 19.04.2021 (Shift-III)]

Correct Answer: (d) Weight - Cubic metre
Solution:The unit of weight is expressed in Newton, not in cubic meters, similar to the unit of force.

Cubic meter or m³ is the unit of volume.

15. Which of the following has the same dimension as that of linear momentum? [S.S.C. Online CGL (T-I) 13.08.2021 (Shift-I)]

Correct Answer: (c) Impulse
Solution:The dimension of impulse is the same as that of linear momentum
Impulse Force x Time (MLT⁻²)(T)=MLT⁻¹

Whereas
Momentum= mass x velocity
MLT⁻¹ = MLT⁻¹
So it is clear that the dimensions of impulse and linear momentum are same.

16. The SI unit of density is _____. [S.S.C. Online MTS (T-I) 14.10.2017 (Shift-II)]

Correct Answer: (a) kg/m⁻³
Solution:The SI unit of density is kilogram/cubic meter or "kg m⁻³ .

17. Which of the following units is used to measure Luminous Intensity? [S.S.C. Online CHSL (T-I) 14.10.2020 (Shift-II)]

Correct Answer: (c) Candela
Solution:The SI unit of Luminous Intensity is the candela (Cd).
QuantitySI Unit NameSymbol
1. LengthMeterm
2. MassKilogramkg
3. TimeSeconds
4. Electric CurrentAmpereA
5. TemperatureKelvinK
6. Amount of SubstanceMolemol
7. Luminous IntensityCandelacd

18. What is the SI unit of time? [S.S.C. JE Civil Exam 23.03.2021 (Shift-II)]

Correct Answer: (d) Second
Solution:The SI unit of time is the second.
Time is a fundamental quantity. Time is a scalar quantity.
QuantitySI Unit NameSymbol
1. LengthMeterm
2. MassKilogramkg
3. TimeSeconds
4. Electric CurrentAmpereA
5. TemperatureKelvinK
6. Amount of SubstanceMolemol
7. Luminous IntensityCandelacd

19. What is the SI unit of Momentum? [S.S.C. Online MTS (T-I) 13.08.2019 (Shift-I)]

Correct Answer: (b) kg m/sec
Solution:Momentum Defined:
Momentum is the product of an object's mass (m) and its velocity (v): p = mv
SI Units:
Mass (m) is measured in kilograms (kg).
Velocity (v) is measured in meters per second (m/s).
Therefore:
 The SI unit of momentum is kg (m/s) = kg·m/s. 

20. Kilowatt-hour (kWh) is the unit of which of the following? [S.S.C. Online MTS (T-I) 18.09.2017 (Shift-III)]

Correct Answer: (d) Energy
Solution:Kilowatt-hour (kWh) is the unit of energy.

A kilowatt-hour (kWh) represents the amount of energy used by a device consuming one kilowatt (1,000 watts) of power for one hour.