Speed, Density and Pressure

Speed

Speed is a measure of how quickly an object moves.
It is a scalar quantity, i.e., it only denotes the magnitude and no direction.
Speed is calculated as the distance travelled divided by the time taken.
Units for speed are commonly m/s or km/h.
To convert speed from km/h to m/s, multiply by 1000 and divide by 3600.
To convert speed from m/s to km/h, multiply by 3600 and divide by 1000.

Density is a measure of mass per volume.
It is calculated as mass divided by volume.
The units of Density are usually g/cm³ or kg/m³.
An object will float in a fluid (a liquid or gas) if it is less dense than the fluid, and sink if it is denser.
To convert density from g/cm³ to kg/m³, multiply by 1000.
To convert density from kg/m³ to g/cm³, divide by 1000.

Pressure is the force exerted per unit area.
It is calculated as force divided by area.
The units of Pressure are usually Pascals (Pa), Newtons per square metre (N/m²), or atmospheres (atm).
Pressure increases with increased force or decreased area.
In the context of fluids, pressure increases with increase in depth, density or gravity.
To convert pressure from Pa to atm, divide by 101325.
To convert pressure from atm to Pa, multiply by 101325.