Question

4. The density of mercury is 13.6 g/cm3 in CGS system.Find its value in SI units.

Answer 1

The height of mercury coloumn in a barometer in Calcutta lab was recoreded to be 75 cm. Calculate this pressure in SI and CGS units using following data: Specific Gravity of mercury = 13.6, Density of water = 1000 kg/metre(cubed), g = 9.8 m/second (squared) at Calcutta. Given P = hpg in usual symbols.

8 years ago

Answers : (1)

Pressure = hpg = (75 cm)(13.6 * 1000 kg/m3)(9.8 m/s2)

SI units

We only need to convert cm to m, since all other units are already SI.

So, pressure in SI units = (0.75 m)(13.6 * 1000 kg/m3)(9.8 m/s2) = 99960 bar

 

CGS units

Here, we need to convert kg/m3 to g/cm3 and m/s2 to cm/s2

1 kg/m3 = 1000 g/m3 * (1 m/100 cm)3  = 1000 g / 1000000 cm3 = 0.001g/cm3.

So 1000 kg/m3 = 0.001 * 1000 g/cm3

= 1 g/cm3

1 m/s2 = 100 cm/s2

So, 9.8



Answer 2

Hey there!

Density's SI unit is kg/m³

So, convert it into kg/m³

i.e 1 cm = 10-² m and 1g = 10-³ kg 

Now, We can convert density of mercury.

13.6 g/cm³

= 13.6 × ( 10-³)/(10-²)³ kg/m³ 

= 13.6 × 10^(-3 + 6) kg/m³ 

= 13.6 × 10³ kg/m³   ← Ans

Hope It Helps You!