Railway Science (Physics-Units and Measurements) (Part-II)

Total Questions: 31

1. Nm⁻² is the SI unit of _______. [RRB Group D 04/10/2018 (Morning)]

Correct Answer: (b) Pressure
Solution:

Physical Quantities and their SI units: Force and Weight - N or kg-ms⁻² . Electric charge - C, Electric potential - V or W/A. Energy, Work, Heat- N⋅m, Inductance- Wb/A. Magnetic flux density- Wb/m² .

2. The Coulomb is the SI Unit of : [RRB Group D 04/10/2018 (Afternoon)]

Correct Answer: (d) electric charge
Solution:

Resistance: SI unit - ohm (Ω). Resistance measures how much an object opposes the flow of electrical current. Electric current: SI unit - Ampere (A). Current measures the rate of flow of electric charge. Potential difference (voltage): SI unit - volt (V).

3. Volt is the SI unit of ________ . [RRB Group D 05/10/2018 (Morning)]

Correct Answer: (c) potential difference
Solution:

Force, Weight (Newton, N), Frequency (Hertz, Hz), Electric charge (Coulomb, C), Inductance (Henry, H), Capacitance (Farad, F), Magnetic flux (Weber, Wb), Magnetic flux density (Tesla,T), Energy, Work, Heat (Joule, J), Resistance (Ohm, Ω), Electric current (Ampere, A).

4. What is the mass per unit volume of a substance called? [RRB Group D 05/10/2018 (Morning)]

Correct Answer: (b) Density
Solution:

Physics Formulas : Pressure= Force/ Area. Weight = mass х acceleration due to gravity. Work = force × displacement. Torque = Force х radius. Force = Mass × acceleration. Kinetic energy = 1/2 × mass × (Velocity)² . Potential energy = Mass × acceleration (g) of free fall × height.

5. _________ measures the speed of work done. [RRB Group D 05/10/2018 (Morning)]

Correct Answer: (d) Power
Solution:

It is measured in watts, which is equal to joules per second. Force is the amount of push or pull that is applied to an object. It is measured in newtons. Pressure is the force per unit area. It is measured in pascals. Energy is the ability to do work. It is measured in joules.

6. Ohm-m is the SI unit of __________ . [RRB Group D 05/10/2018 (Afternoon)]

Correct Answer: (a) Resistivity
Solution:

Resistivity is a property of a material that naturally hinders the flow of electric current. It quantifies the resistance for a given length and area of the material. SI Units: Electric potential - Volt, Inductance - Henry, Capacitance - Farad, Resistance and Impedance - Ohm, Magnetic flux - Weber, Magnetic flux density - Tesla.

7. Which of the following pairs do not have the same units ? [RRB Group D 05/10/2018 (Afternoon)]

Correct Answer: (d) Force and Pressure
Solution:

Force: Measured in Newtons (N), which represent the push or pull experienced by an object. Pressure: Measured in Pascals (Pa), which represent force applied per unit area. Speed and Velocity: Both are measured in meters per second (m/s). Work and Energy: Both are measured in Joules (J). Distance and Displacement: Both are measured in meters (m).

8. 1 Coulomb/1s = _______ [RRB Group D 12/10/2018 (Evening)]

Correct Answer: (b) 1 ampere
Solution:

Ampere (A): This is the unit of electric current, which is defined as the rate of flow of electric charge. Therefore, 1 Coulomb/1s is exactly equal to 1 ampere. Volt (V) : This is the unit of electric potential difference. Watt (W): This is the unit of power.

9. 1 Joule = _________ [RRB Group D 15/10/2018 (Afternoon)]

Correct Answer: (d) 1 N × 1 m
Solution:

SI Units of work or energy - Joule (J). 1 Joule is defined as the work done or energy transferred to an object when a one Newton force acts on it over one meter. Pressure (P) - It is force applied per unit area and in SI units it is pascal which is 1 Pascal = 1N/m.

10. 1 Newton = ? [RRB Group D 22/10/2018 (Afternoon)]

Correct Answer: (c) 1 kg m s⁻²
Solution:

Newton (N): This is the SI unit of force. It represents the amount of force required to accelerate a mass of 1 kilogram at a rate of 1 meter per second. Kilogram (kg): This is the SI unit of mass. Meter (m): This is the SI unit of length. Second (s): This is the SI unit of time.