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

Total Questions: 31

11. If momentum (p) and velocity (v) are given, then the formula used to find mass (m) will be: [RRB Group D 22/10/2018 (Evening)]

Correct Answer: (b) 𝑃/𝑚
Solution:

Momentum (p) is defined as the product of mass (m) and velocity (v). The dimensional equation of momentum is p = [ M¹L¹T⁻¹].

12. What is the international (SI) unit of momentum? [RRB Group D 23/10/2018 (Morning)]

Correct Answer: (b) Kg ms⁻¹
Solution:

Unit Name and SI Unit: Force - Newton, Frequency - Hertz, Electric charge - Coulomb, Electric potential (Voltage) - Volt, Heat - Joule, Power - Watt, Magnetic flux - Weber.

13. Which of the following is NOT a unit that measures temperature ? [RRB Group D 31/10/2018 (Afternoon)]

Correct Answer: (b) Pascal
Solution:

Pascal is a unit of pressure. Fahrenheit (expressed as °F), Celsius (°C), and Kelvin (K) are the scales used in thermometers (a device used to measure temperature).Temperatures on different scale - Freezing point of water: 32 °F (Fahrenheit) = 0°C (Celsius) = 273 K (Kelvin), Boiling point of water: 212°F =100°C = 373.15K respectively.

14. 𝑁𝑚⁻² is the international (SI) unit of _________. [RRB Group D 5/11/2018 (Morning)]

Correct Answer: (d) pressure
Solution:

Nm⁻² stands for Newton per square meter. This unit is commonly known as the pascal (Pa), which is the SI unit of pressure. Pressure is defined as force per unit area.

15. Which of the following pairs have the same units? [RRB Group D 16/11/2018 (Afternoon)]

Correct Answer: (a) Work and Energy
Solution:

The standard unit of energy and work is the joule (J). SI unit: Pressure (Pascal), Force (Newton), Electric current (Ampere), Amount of substance (Mole), Luminous intensity (Candela).

16. Which one of the following does NOT relate to force ? [RRB Group D 11/12/2018 (Morning)]

Correct Answer: (b) kg ms⁻¹
Solution:

It is the unit of Momentum (Other units are Newton seconds). Force is defined as the rate of change of momentum, or the product of mass and acceleration. The SI unit of force is the Newton (N), which is equivalent to 1 kg ms⁻² .

17. _______ is the SI unit of temperature. [RRB Group D 14/12/2018 (Evening)]

Correct Answer: (c) Kelvin
Solution:

SI Units: Length - meter (m), Time - second (s), Amount of substance - mole , Electric current - ampere (A), Luminous intensity - candela (cd),and Mass - kilogram (kg).

18. Which of the following physical quantities measures the rate of work done? [RRB ALP Tier - I (14/08/2018) Afternoon]

Correct Answer: (b) Power
Solution:

It can be defined as the rate of doing work, it is the work done in unit time. SI unit Watt (W) which is Joules per second (J/s). Energy is the ability to do work (SI unit - Joule). Momentum is the quantity that is used to describe the state of motion of an object with a non-zero mass (SI unit - kilogram meter per second).

19. One nanometer is: [RRB ALP Tier - I (17/08/2018) Evening]

Correct Answer: (a) 10⁻⁹ m
Solution:

A nanometer is a very small unit of length. Terameter (1 Tm) - 10¹² m. Gigameter (1 Gm) - 10⁹ m. Megameter (1 Mm) - 10⁶ m. Kilometer (1 Km) - 10³ m. Decimeter (1 dm) - 10⁻¹ m. centimeter (1 cm) - 10⁻¹² m. Millimeter (1 mm) - 10⁻³ m. Micrometer (1 μm) - 10⁻⁶ m. Nanometer (1 nm) - 10⁻⁹ m. Picometer (1 pm) - 10⁻¹² m.

20. The SI unit of electric current is: [RRB ALP Tier - I (20/08/2018) Morning]

Correct Answer: (c) ampere
Solution:

Electric current - Physical phenomenon of flow of an electric charge (usually of electrons) by means of a conductive material. Silver is the best conductor of electricity. The conventional direction of an electric current is the direction in which a positive charge would move. Electric potential difference - Volt. Microampere (µA) = 10⁻⁶A.