Railway Science (Physics-Force and Pressure) (Part-III)

Total Questions: 50

1. What is the definition of mass? [RRB Group D 24/10/2018 (Evening)]

Correct Answer: (d) The amount of matter in an object is called the mass of that object.
Solution:

Mass can be stated as the measure of the quantity of matter in an object. The SI unit of mass is the kilogram (kg). The mass of an object is constant and does not change from place to place.

2. In negative acceleration, the velocity of a body_________. [RRB Group D 25/10/2018 (Morning)]

Correct Answer: (c) decreases
Solution:

Negative acceleration, also known as deceleration or retardation, occurs when the speed of an object decreases over time. It signifies motion’s opposing force, where the object is slowing down rather than speeding up.

3. What is the upward force exerted by the water on the bottle containing it called ? [RRB Group D 29/10/2018 (Morning)]

Correct Answer: (b) Buoyant Force
Solution:

It is the force that causes objects to float. Unit - Newton (N). It depends upon the density of the fluid. Formula : Buoyant force (f) = ρgv. Where ρ - density, g - gravity, and v - volume. Tension - It is the pulling force that is applied axially by a rope, cable, etc. Thrust force - Force that pushes or accelerates the object in one direction. It is based on Newton's third law of motion. Pressure - Force applied perpendicular to the surface of an object per unit area.

4. Instantaneous velocity and average velocity are equal when the object _____. [RRB Group D 2/11/2018 (Afternoon)]

Correct Answer: (b) has zero acceleration
Solution:

The average velocity tells us how fast an object has been moving over a given time interval but does not tell us how fast it moves at different instants of time during that interval. For this, we define instantaneous velocity or simply velocity v at an instant t.

5. Which of the following examples illustrates Newton's first law of motion? [RRB Group D 5/11/2018 (Evening)]

Correct Answer: (b) When a bus starts suddenly, the passengers receive a backward jerk
Solution:

First law - An object at rest remains at rest, or if in motion, remains in motion at constant velocity unless acted on by a net external force. Newton's first law of motion is known as Law of Inertia. Example : Brakes applied by a bus driver abruptly, A ball rolling on the ground, etc. Third Law of motion : Every action has an equal and opposite reaction. Example - Rocket launch.

6. When the angle between the force and the displacement is 90°, the work done is______. [RRB Group D 5/11/2018 (Evening)]

Correct Answer: (c) zero (no work is done)
Solution:

Work done on an object : The magnitude of the force multiplied by the distance moved by the object in the direction of the applied force. Unit (Work) - Joule. When angle is 180°C - work done is considered as negative and when angle is 0°C , then work done is positive.

7. If a body, in transformed motion, moves on a curved path, then this motion is called ______. [RRB Group D 12/11/2018 (Afternoon)]

Correct Answer: (d) curvilinear motion
Solution:

It refers to the motion of a body along a curved path. This type of motion occurs when the direction of the body changes continuously as it moves. Examples of curvilinear motion include the motion of a projectile, the motion of planets around the sun, or the motion of a car around a bend.

8. During a motorcycle accident, a helmet is helpful in reducing __________. [RRB Group D 15/11/2018 (Evening)]

Correct Answer: (a) impulse
Solution:

This is the product of force and time (impulse = force × time). In a motorcycle accident, the impact with the ground or another object creates a large force acting on the head for a short duration. velocity is the speed at which something moves in a particular direction. It is a vector quantity.

9. An example of stretching is: [RRB Group D 27/11/2018 (Evening)]

Correct Answer: (a) flag hoisting
Solution:

When done with proper form (arms extended, back straight), this action involves extending and elongating the muscles in the arms, shoulders, and back, which is the essence of stretching.

10. The speed of a car on a crowded street is an example of________. [RRB Group D 28/11/2018 (Morning)]

Correct Answer: (a) Non-uniform motion
Solution:

It is a type of motion in which an object moves at different speeds. Examples of Non-uniform Motion: A man running in a 100m race, and A bouncy ball.