Physics (Part-II) (Railway)

Total Questions: 50

1. One nanometer is: [RRB ALP & Technician Exam, 17.08.2018 Shift-III]

(1) 10-¹¹ m
(2) 10-⁹ m
(3) 10-⁸ m
(4) 10-¹⁰ m

Correct Answer: (2) 10-⁹ m

Solution:A nanometer is a unit of spatial measurement that is 10-⁹ meter, or one billionth of a meter. It is commonly used in nanotechnology, for the building of extremely small machines.

2. If the initial velocity of a car is 5 m/s, and the final velocity is 10 m/s in 5 s, then the acceleration is________. [RRB ALP & Technician Exam, 17.08.2018 Shift-III]

(1) 5 m/s²
(2) 10 m/s²
(3) 0.1 m/s²
(4) 1 m/s²

Correct Answer: (4) 1 m/s²

Solution:v=u+ at

where, v = 10m / s,

u = 5m / s, t = 5s

Now, 10 = 5 + a * 5

5 = 5a

a = I m/s²

3. If a body is whirled in a circle, then the work done on it________. [RRB ALP & Technician Exam, 17.08.2018 Shift-III]

(1) is zero
(2) cannot be determined
(3) is positive
(4) is negative

Correct Answer: (1) is zero

Solution:When the body is whirled in a circle, then the work done on it is zero. Because work done is defined as the distance an object is moved in the direction of the force applied and since the centripetal force acts perpendicular to the velocity (direction of motion) the work done is zero. Work done by centripetal force is zero only when radial position does, not change.

4. The rate of change of velocity is called: [RRB ALP & Technician Exam, 17.08.2018 Shift-III]

(1) Momentum
(2) Acceleration
(3) Speed
(4) Force

Correct Answer: (2) Acceleration

Solution:The rate of change of velocity is called acceleration. Acceleration is a vector quantity and having both magnitude and direction. It is measured in meters per second squared or meters per second (the object's speed or veloçity per second.

5. What is the Centre of Curvature of a spherical mirror? [RRB ALP & Technician Exam, 17.08.2018 Shift-III]

(1) It is the centre of a hollow sphere of which the spherical mirror is a part.
(2) It is the midpoint of a spherical mirror.
(3) It is a point from which the rays of light appear to be coming from on the principal axis of a convex mirror.
(4) It is the point on the principal axis through which rays of light parallel to the principal axis pass after reflection.

Correct Answer: (1) It is the centre of a hollow sphere of which the spherical mirror is a part.

Solution:The Center of Curvature of a spherical mirror is the point in the center of the mirror which passes through the curve of the mirror and has the same tangent and curvature at that point or the point in the center of the sphere from which the mirror was sliced is known as the center of curvature.

6. A compressed spring possesses more energy than a spring of normal length because the compressed spring has: [RRB ALP & Technician Exam, 20.08.2018 Shift-I]

(1) chemical energy
(2) potential energy
(3) kinetic energy
(4) heat energy

Correct Answer: (2) potential energy

Solution:The energy possessed by a body on account of its position or configuration (shape and size) is called potential energy. When a spring is com pressed or stretched, work done in compressing or stretching is stored in the form of potential energy. The energy stored is greater than that possessed by a spring of normal length.

7. The diameter of the reflecting surface of a spherical mirror is called a/an: [RRB ALP & Technician Exam, 20.08.2018 Shift-I]

(1) aperture
(2) principal axis
(3) pole
(4) focus

Correct Answer: (1) aperture

Solution:The diameter of the reflecting surface of spherical mirror is called its aperture. In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture and focal length of an optical system determine the cone angle of a bundle of rays that come to a focus in the image plane.

8. This is NOT a use of a concave mirror: [RRB ALP & Technician Exam, 20.08.2018 Shift-I]

(1) In torches
(2) As shaving mirrors
(3) As rear view mirrors
(4) In headlights

Correct Answer: (3) As rear view mirrors

Solution:Convex mirror is used in rear view mirror of vehicles: so that the driver can see the traffic coming from behind. The field of view is widest in case of a convex mirror, which enables it to show a wider area from behind.

9. What is the principal focus of a spherical mirror? [RRB ALP & Technician Exam, 20.08.2018 Shift-III]

(1) It is a point from which the rays of light appear to be coming from on the principal axis of a convex mirгог.
(2) It is the point on the principal axis through which rays of light parallel to the principal axis pass after reflection or appear to be arising from this point on the principal axis.
(3) It is the centre of a hollow sphere of which the spherical mirror is a part.
(4) It is the midpoint of a spherical mirror.

Correct Answer: (2) It is the point on the principal axis through which rays of light parallel to the principal axis pass after reflection or appear to be arising from this point on the principal axis.

Solution:The principal focus of a spherical mirror is a point on the principal axis of the spherical mirror at which, the light rays which are parallel to the principal axis actually converge (meet) or appear to diverge after reflection.

10. Definition of Force can be stated from: [RRB ALP & Technician Exam, 20.08.2018 Shift-III]

(1) Newton's second law of motion
(2) Newton's first law of motion
(3) Newton's third law of motion
(4) Newton's law of gravitation

Correct Answer: (1) Newton's second law of motion

Solution:Newton's second law of motion defines a force to be equal to the change in momentum with a change in time. It states that the acceleration of an object is directly proportional to the net force acting on it, and inversely proportional to its mass. It gives F=ma.

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