Question 1

What is the SI unit of temperature?

Accepted Answer

The SI unit of temperature is Kelvin (K), named after physicist William Thomson, 1st Baron Kelvin. It is an absolute temperature scale where 0 K represents absolute zero, the lowest possible temperature.

Question 2

Which of the following is the SI unit of force?

Accepted Answer

The SI unit of force is Newton (N), named after Sir Isaac Newton. It is defined as the force required to accelerate a mass of 1 kilogram at a rate of 1 meter per second squared (1 kg⋅m/s²).

Question 3

What is the SI unit of electric current?

Accepted Answer

The SI unit of electric current is Ampere (A), named after French physicist André-Marie Ampère. It is defined as the flow of one coulomb of charge per second (1 A = 1 C/s).

Question 4

Which of the following best describes the law of conservation of energy?

Accepted Answer

The law of conservation of energy states that energy cannot be created or destroyed; it can only be transformed from one form to another. The total energy in an isolated system remains constant.

Question 5

Which scientist formulated the law of universal gravitation?

Accepted Answer

Sir Isaac Newton formulated the law of universal gravitation in the late 17th century. This law states that every mass attracts every other mass with a force proportional to the product of their masses and inversely proportional to the square of the distance between them (F = G m₁m₂/r²).

Question 6

When a person stands in front of a plane mirror, the image formed is always:

Accepted Answer

A plane mirror always forms a virtual, erect, and same-sized image of an object placed in front of it. The image distance equals the object distance, and the image is laterally inverted (left-right reversed).

Question 7

Which of the following is the SI unit of electric current?

Accepted Answer

The SI unit of electric current is the Ampere (A), named after French physicist André-Marie Ampère. It is defined as the flow of one coulomb of charge per second.

Question 8

What is the SI unit of force?

Accepted Answer

The Newton (N) is the SI unit of force, named after Sir Isaac Newton. One Newton is defined as the force required to accelerate a mass of one kilogram at a rate of one meter per second squared (1 N = 1 kg⋅m/s²).

Question 9

Which physicist formulated the law of universal gravitation?

Accepted Answer

Sir Isaac Newton formulated the law of universal gravitation in 1687. This law states that every particle of matter in the universe attracts every other particle with a force proportional to the product of their masses and inversely proportional to the square of the distance between them.

Question 10

What is the speed of light in vacuum according to modern physics?

Accepted Answer

The speed of light in vacuum is approximately 3 × 10⁸ meters per second (m/s), or more precisely 299,792,458 m/s. This is a fundamental constant in physics, denoted by the symbol 'c', and is the maximum speed at which energy or information can travel.

Question 11

Which of the following is an example of a scalar quantity in physics?

Accepted Answer

A scalar quantity is a physical quantity that has only magnitude (size) and no direction. Examples include mass, temperature, speed, distance, and time. In contrast, vector quantities have both magnitude and direction, such as velocity, displacement, and force.

Question 12

A person standing on the ground observes that the angle of elevation to the top of a building is 30°. If the person moves 10 meters closer to the building, the angle of elevation becomes 45°. What is the approximate height of the building?

Accepted Answer

This is a trigonometry problem based on angle of elevation, a fundamental physics/mathematics concept tested in SSC GD. Using tan(30°) = h/(d+10) and tan(45°) = h/d, where h is height and d is initial distance, we can solve: h = d·tan(45°) and h = (d+10)·tan(30°). Since tan(45°) = 1 and tan(30°) = 1/√3, we get d = (d+10)/√3, which gives d = 10(√3)/(√3-1) ≈ 13.66 m. Therefore, h ≈ 13.66 m or approximately 13.7 meters.

Question 13

A person standing on the ground observes a bird flying at a constant height. From the observer's perspective, which of the following statements about the bird's motion is CORRECT?

Accepted Answer

The bird is moving at constant velocity (constant speed and direction) relative to the ground. From the ground observer's reference frame, the bird has zero acceleration even though it is in motion. This tests the distinction between velocity (rate of change of position) and acceleration (rate of change of velocity).

Question 14

A ball is dropped from a height of 20 meters on Earth (g = 10 m/s²). Ignoring air resistance, what is the velocity of the ball just before it hits the ground?

Accepted Answer

Using the kinematic equation v² = u² + 2as, where u = 0 (dropped, not thrown), a = g = 10 m/s², and s = 20 m, we get v² = 0 + 2(10)(20) = 400, so v = 20 m/s. This tests application of kinematic equations in free fall scenarios.

Question 15

A person pulls a box across a rough floor with a rope at an angle of 30° above the horizontal. Which force component is MOST effective in moving the box forward?

Accepted Answer

The horizontal component of the applied force (F cos 30°) is responsible for moving the box forward. The vertical component (F sin 30°) reduces the normal force and friction, but the horizontal component is the primary mover. This tests understanding of force resolution and vector components in everyday mechanics.

Question 16

A car traveling at 20 m/s suddenly applies brakes and comes to rest in 5 seconds. Assuming uniform deceleration, what is the magnitude of acceleration during braking?

Accepted Answer

Using a = (v - u) / t, where v = 0 m/s (final velocity), u = 20 m/s (initial velocity), and t = 5 s, we get a = (0 - 20) / 5 = -4 m/s². The magnitude is 4 m/s². This tests understanding of acceleration as a vector quantity and its calculation in real-world braking scenarios.

Question 17

A light bulb rated at 60 W operates at 220 V. What is the electrical resistance of the bulb's filament?

Accepted Answer

Using P = V² / R, where P = 60 W and V = 220 V, we get R = V² / P = (220)² / 60 = 48,400 / 60 ≈ 806.67 Ω. This tests understanding of the relationship between power, voltage, and resistance in everyday electrical devices.

Question 18

A student observes that when a metal rod is heated at one end, the heat gradually spreads to the other end. Which of the following best explains this phenomenon and identifies the primary mode of heat transfer in solids?

Accepted Answer

In solids, heat is primarily transferred through conduction. When a metal rod is heated, the atoms at the heated end vibrate more vigorously. These vibrating atoms collide with neighboring atoms, transferring kinetic energy to them. This process continues along the length of the rod without any bulk movement of the material itself. Metals are excellent conductors of heat because they contain free electrons that can also carry thermal energy rapidly through the lattice structure.

SSC GD Constable Physics — Everyday Concepts

Physics — Everyday Concepts— Rules & Concept

Key Points to Remember

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Physics — Everyday Concepts — Practice Questions

60-Second Revision — Physics — Everyday Concepts