INTRODUCTION TO DENSITY
The density of any substance is defined as it’s mass per unit volume. P= m/v ………………(1)
Recall,
L x L or L²= Area (A)
Area is also = πr²
A x L= Volume (V) L x L x L or L³= Volume (V)
Where,
P= density
m= mass
V= volume L= length
A=area
r= radius of the object
π= 22/7
If volume is not given, but radius and height or length is given. We use the formula
P = m/πr² x h …………….(2)
P= m/A x h …………………..(3)
To calculate the mass,
m= Pv …………….(4) or m = PAh …………..(5)
To calculate the volume,
V= m/P………….(6)
To calculate the height,
h= m/PA ……..(7) or h= m/Pπr² Relative density,
Relative density is the density of water compared with the density of other substances.
R.D = density of substance/density of water.
R.D = Upthrust in Liquid/Upthrust in water It has no unit.
Upthrust,
When a body is immersed completely or partially in a liquid, the fluid exerts an upward force on the body (Archimede’s principle). This upward force is known as Upthrust. Upthrust is equal to the weight of the fluid displace by the body. This Upthrust is what we know as loss in weight.
To calculate the lost in weight of the object or weight of fluid displaced, we say Upthrust of the object(lost in weight)= W1-W2
Where,
W1 =weight in air
W2 = weight in liquid
Therefore we can calculate the R.D as R.D = W1/W1-W2
Which is,
Upthrust in air/Upthrust in Liquid=R.D
W= V(P-Pf)g Or
W= 4πr³/3 (P-Pf)g (use this formula if volume is not given directly)
Where,
W= weight of fluid displaced
V= volume of fluid displaced
P and Pf = density of object and fluid respectively. Congrats! you’ve finished learning.

click https://sub4learn.science.blog/2020/08/01/calculations-on-density/
for calculations

source: www.sub4learn.science.blog

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