Mechanics (Part –1)

• One electron volt is equal to the energy present in an electron or a charged particle of unit charge.
• 1 eV = 1.602 × 10⁻¹⁹ J.

1. The Fundamental quantity is independent physical quantity that is impossible to express in other physical quantities, like-Length and Time. Therefore mass is fundamental quantity.
2. Mass is a physical quantity because by the laws of physics it can be expressed in terms.
3. Mass is a scalar quantity, as it has only magnitude.

Hence option (d) will be the correct answer.

Relative Density is a ratio, so it has no unit.

The formula of relative density is -

Relative Density =Density of Substance/Density of Water

Hence, Relative density is a dimensionless quantity, therefore there is no SI Unit of relative density.

Relative Density is a ratio, so it has no unit.

The formula of relative density is -

Relative Density =Density of Substance/Density of Water

Hence, Relative density is a dimensionless quantity, therefore there is no SI Unit of relative density.

i.e. Density p =Mass (m) /Volume (v)

The SI unit of density is kg/m³.

Hence the density of the material of a substance (p) is its mass (m) divided by the volume (V).

• Momentum =Mass × Velocity
• Momentum is a vector quantity.
• The SI unit of momentum is a kilogram meter per second.
• It is also called Newton second.

Angular Momentum is a vector quantity.

Vector Quantities

Definition:
A vector quantity has both magnitude and direction.

Examples of Vectors:

• momentum,
• impulse,
• acceleration,
• force,
• displacement,
• velocity,
• weight,
• electric field.
• torque,
• magnetic field,
• magnetic induction,
• angular momentum,
• magnetic moment, etc.