#### Density and Pressure

**Density**

*Density*=^{Mass}/_{Volume}- To measure the density of a liquid:
- Place a measuring cylinder on a balance
- Fill the measuring cylinder with the liquid
- The change in mass is the mass of the liquid, and the volume is shown on the scale.
- Then use the formula.

- To get the density of a solid:
- Find the volume:
- To find the volume of a regular object, use its mathematical formula.
- If the object is irregular, put the object into a measuring cylinder with water, and the rise of the water is the volume of the object.

- Find the mass: Weigh the object on a scale
- Then use the formula.

- Find the volume:

__Flotation__

__Flotation__

- The density of water is 1 g/cm
^{3}, if an object has a greater density than that, it will sink in water, and if the object’s density is less than that, then it will float in water. - For example, an orange with its peel has a density of 0.84 g/cm
^{3}, we can predict that it will float because it is less than 1 g/cm^{3}. We can also say that an orange without its peel, which has a density of 1.16 g/cm^{3}will sink because it is greater than 1 g/cm^{3}

*Photo Credit:*CSIRO’s Tweet

**PRESSURE**

**Pressure in Solids**

*Pressure (Pa)*=^{Force (N)}/_{Area (m2)}*P*=^{F}/_{A}- Unit: Pascals (Pa) =
^{N}/_{m2}

**Pressure in Liquids**

*Pressure (Pa)*=*Density (*×^{kg}/_{m3})*Gravity (*×^{m}/_{s2})*Height (m)*- P = hρg
- At a depth of 10 m in water, the pressure is always 100 000 Pa (1 bar) and is constant for each further 10 m.

**Atmospheric Pressure**

- 1 atm = 101.325 × 10
^{3}Pa = 101kPa

*Photo Credit: Manometer *(ACSMASIndia.com), *Barometer *(Brainly.in)

**Manometer**

- A manometer measures pressure difference.
- The height difference shows the excess pressure in addition to the atmospheric pressure

**Barometer**

- A barometer is a tube with vacuum at the top and mercury filling the rest.
- The pressure of the air pushes down on the reservoir, forcing mercury up the tube.
- Measure the height of the mercury.
- 1 atm is approximately 760 mm of mercury.

__Examples__

__Examples__

- A shape with dimensions 5 cm × 4 cm × 2 cm. It has a mass of 100 g. What is the density of the material?
*Density*=^{Mass}/_{Volume}- Mass = 100 g
- Volume = 5 × 4 × 2 = 40 cm³
- ∴ Density = 100/40
- ∴ Density = 2.5 g/cm³