Worked Examples-Calculation Part 1 - Work, Energy and Power

Considered Formula;

$$\text {i)}\quad W.d = F \times d$$ $$\qquad \text {Where}~~W.d \to Work~done,\quad F \to Force \\\qquad d \to Distance~moved$$ $$\text {ii)}\quad K.E = \frac {1}{2}mv^2$$ $$\qquad \text {Where}~~K.E \to Kinetic~energy,\quad m \to Mass \\\qquad v \to Velocity$$

Example

Abu Nufayl lifts a sack of rice by a force of 250 N against gravity to 2 m high. Calculate his work done

Solution

Data given

Force (F) =250 N

Distance (d) = 2 m

Work done (W.d) =?

$$~~~~~~~~~~~~~~~~~~~~~~~~~~~~W.d = F \times d$$ $$~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ = 250 \times 2$$ $$~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ = 500~Joules$$

The work done by Abu Nufayl = 500 Joules     CONTINUE READING

Measurement of Temperature

Temperature is measured by thermometer on physical properties that change linearly with temperature to give temperature readings. Physical properties of a thermometer include;

i)        Expansion of liquid (mercury or alcohol) when heated

ii)       Expansion of a compound strip of two metals

iii)     Thermoelectric property change in which when junction of two different metals are heated an electric current is generated

iv)     Change of resistance of a wire e.g. platinum resistance thermometer

Thermometric Scales

There are two scales of thermometer include;

i)        Celsius or Centigrade Scale

ii)       Fahrenheit Scale

Celsius or Centigrade Scale

This scale has 100 divisions between the upper and lower standard points. This scale was introduced by   CONTINUE READING

Warning Signs

Warning sign is the symbol established to ensure safety in the laboratory and in other field like goods or commodities. This signs should have obeyed to avoid accidents, include Toxic, Harmful/Irritant, Flammable, Oxidizing agent, etc

Flammable

Flammable symbol means that the substance can catch fire easily. For Example, , gasoil, kerosene, petrol, butane, methane, spirit, nail polish remover, turpentine etc.

Toxic

Toxic symbol means that a substance is dangerous and can cause death within a short time. Toxic substances containing poisonous ingredients, Example, of toxic substance is jik, mercury etc. 

Oxidizing Agent

Oxidizing agent symbol means that the substance can speed up the rate of burning. For Example, oxygen gas, chlorine gas, fluorine gas and   CONTINUE READING