Worked Examples on Archimedes Principle

Considered Formula

$$\text {i)}\quad R.D = \frac {W_a - W_l}{W_a - W_w}$$ $$\qquad \text {Where}~~R.D \to Relative~density,\quad W_a \to Weight~in~air \\\qquad W_l \to Weight~in~liquid, \qquad W_w \to Weight~in~water$$ $$\text {ii)}\quad R.D = \frac {\rho_s}{\rho_w}$$ $$\qquad \text {Where}~~R.D \to Relative~density,\quad \rho_s \to Density~of~substance \\\qquad \rho_w \to Density~of~water$$

Example 1

A piece of glass weight in air 1.2N and 0.7N when completely immersed in water calculate it’s.

a)    Relative density

b)    Density of glass

c)     Volume of glass

(Density of water = 1g/cm³)

Solution

Data given

Weight in air (W_a) = 1.2 N

Weight in water (W_w) = 0.7 N

Density of water (ρ_w) = 1g/cm³

a)        Relative density (R.D) = ?

$$~~~~~~~~~~~~~~~~~~~~~~~~~~~~R.D = \frac {W_a}{W_a - W_w}$$ $$~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ = \frac {1.2}{1.2 - 0.7}$$ $$~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ = \frac {1.2}{0.5}$$ $$~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ = \frac {1.2 \times 10}{0.5 \times 10}$$ $$~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ = \frac {12}{5}$$ $$~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ = 2.4$$

          The relative density = 2.4

b)  CONTINUE READING

Effects of Forces

Forces have several effects on objects. These effects include: - 

(i)                  Stretching and Restoring force

(ii)                Torsion force

(iii)              Attraction force

(iv)              Friction force

(v)                Compression force

(vi)              Viscosity

(vii)            Repulsion force

(viii)          Air Resistance 

 

Stretching and Restoring

Stretching force is the force produce elongation of object if pulled. For Example, when spring is pulled the stretching force elongate the spring

Air Resistance 

Is the force that resists the movement of an object through the air.

Example of this .....   CONTINUE READING