Write down the SI Units for the following physical quantities. a) Density b) Force c) Energy
The correct answer and explanation is:
Here are the SI units for the given physical quantities:
a) Density
The SI unit of density is kilogram per cubic meter (kg/m³).
b) Force
The SI unit of force is the newton (N).
c) Energy
The SI unit of energy is the joule (J).
Explanation:
Density is defined as mass per unit volume. It describes how much mass is contained in a given volume of a substance. Since the SI unit of mass is the kilogram (kg) and the SI unit of volume is the cubic meter (m³), density is expressed in kilograms per cubic meter (kg/m³). This unit indicates how heavy an object is for a certain space it occupies. For example, water has a density of approximately 1000 kg/m³, meaning each cubic meter of water has a mass of about 1000 kilograms.
Force is any interaction that, when unopposed, changes the motion of an object. According to Newton’s second law, force is the product of mass and acceleration (F = m × a). Mass is measured in kilograms (kg), and acceleration is measured in meters per second squared (m/s²). Multiplying these gives the unit of force as kg·m/s², which is named the newton (N). One newton is the force needed to accelerate a 1 kg mass by 1 m/s². The newton is a derived SI unit and is fundamental in mechanics and engineering.
Energy represents the capacity to do work. It can take many forms, including kinetic energy, potential energy, thermal energy, etc. The SI unit of energy is the joule (J). One joule is defined as the amount of energy transferred when a force of one newton moves an object one meter in the direction of the force. Mathematically, this can be expressed as 1 joule = 1 newton × 1 meter = 1 kg·m²/s². Energy units are crucial in physics, chemistry, and everyday life for measuring heat, work, and power consumption.
In summary, density, force, and energy have distinct SI units that reflect their physical definitions and the fundamental units they derive from, allowing consistent measurement and understanding across scientific disciplines.