April 2024

Elastic Collision is that collision during which

A. Momentum is conserved
B. Energy is conserved
C. Mass is conserved
D. Angular Momentum is conserved

A. Momentum is conserved

An elastic collision is a special type of collision where two key properties are conserved:

A. Momentum is conserved B. Energy is conserved (specifically, kinetic energy)

This means the total momentum and total kinetic energy of the objects before the collision are equal to the total momentum and total kinetic energy of the objects after the collision.

Here’s a breakdown of the other options:

  • C. Mass is conserved: This is true for all collisions (elastic or inelastic) as well as most other physical processes. Mass cannot be created or destroyed according to the law of conservation of mass.
  • D. Angular Momentum is conserved: This can be true for elastic collisions under specific conditions, but it’s not a general requirement for them.

So, for an elastic collision, both momentum and kinetic energy are conserved.

If we are seeking the option that best describes what happens during an elastic collision, the answer would be:

A. Momentum is conserved

Elastic Collision is that collision during which Read More »

The unit vector of a vector A magnitude 2 is

A. 2A
B. A2 
C. A/2
D. A2/2

C. A / 2

he unit vector of vector A (magnitude 2) is:

C. A / 2

Here’s why:

  • A unit vector has a magnitude of 1. It represents the direction of the original vector but with a scaled down length of 1 unit.
  • To find the unit vector, we take the original vector (A) and divide it by its magnitude.

In this case, the magnitude of the vector is given as 2. So:

Unit vector of A = A / |A| = A / 2

Therefore, option C (A / 2) is the correct answer.

The unit vector of a vector A magnitude 2 is Read More »

If a vector is denoted by A then its x-component can be written as

A. Asinθî
B. Asinθĵ
C. Acosθî
D. Acosθĵ

C. Acosθî

The correct answer is:

C. Acosθî

Here’s why:

  • A vector can be represented by its magnitude (A) and direction.
  • In a rectangular coordinate system, we use unit vectors î for the x-axis and ĵ for the y-axis.
  • The x-component of the vector represents the contribution of the vector along the x-axis.
  • To denote this contribution, we use the magnitude (A) multiplied by cosine (cos) of the angle (θ) the vector makes with the positive x-axis. Cosine tells us the relative length of the vector projected onto the x-axis.
  • Therefore, Acosθî represents the x-component of vector A.

Similarly, A sinθĵ would represent the y-component of vector A.

If a vector is denoted by A then its x-component can be written as Read More »

Resistance of a conductor is directly proportional to

A. Length
B. Cross-Sectional Area
C. Magnetic Field
D. N.O.T

A. Length

The resistance of a conductor is directly proportional to its length and inversely proportional to its cross-sectional area. This relationship is described by the formula:

𝑅=𝜌⋅𝐿𝐴

Where:

  • 𝑅 is the resistance,
  • 𝜌 is the resistivity of the material,
  • 𝐿 is the length of the conductor, and
  • 𝐴 is the cross-sectional area of the conductor.

So, the correct answer is:

A. Length

Resistance of a conductor is directly proportional to Read More »

Photo cell works on the principle of

A. Photoelectric effect
B. Compton Effect
C. Pair production
D. None of these

A. Photoelectric effect

A photocell works on the principle of the A. Photoelectric effect.

The photoelectric effect describes the phenomenon where light striking a material can eject electrons from that material. In a photocell, this principle is used to convert light energy into electrical energy.

Compton Effect, Pair Production, and other options you provided are different ways light interacts with matter, but they are not the primary working principle behind photocells.

Photo cell works on the principle of Read More »

The centripetal force through which the moon orbits the earth is equal to

A. Gravitational force of earth on moon
B. Gravitation force of moon on earth
C. Gravitational Force of sun on moon
D. Gravitational force of moon on sun

A. Gravitational force of earth on moon

The centripetal force that keeps the moon in its orbit around Earth is:

A. Gravitational force of earth on moon

Here’s why:

  • Centripetal force is an inward force required for any object moving in a circular path.
  • The Moon’s motion around Earth is nearly circular.
  • Earth’s gravity acts on the Moon, pulling it inwards. This inward pull acts as the centripetal force, constantly “changing the direction” of the Moon’s motion to keep it following a curved path around Earth.

While the Moon also exerts a gravitational force on Earth (as described by Newton’s Third Law), it’s Earth’s gravity that dominates in this scenario and provides the necessary centripetal force for the Moon’s orbit.

The centripetal force through which the moon orbits the earth is equal to Read More »

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