Question

1. What are the uses of coal?
2. List about condition under which combustion taxes place?
3. Why sportsman uses shoes with spikes ?
4. Give two example situation in which you push or pull to change the state of motion of object ?
5. What is LED ? how can small current be tested ?​

Answer 1

$\large{\bf{\blue{\underline{\underline{Hi....!! }}}}}$

$1$Coal has many important uses worldwide. The most significant uses of coal are in electricity generation, steel production, cement manufacturing and as a liquid fuel. Different types of coal have different uses. Steam coal - also known as thermal coal - is mainly used in power generation.

$2$.Following are the conditions under which combustion can take place: Presence of oxygen. Presence of inflammable substance. Ignition temperature.

$3$.Sportsmen use shoes with spikes so as to have a better grip while running. This is because the force of friction between the shoes and the ground increases with the help of spikes.

$4$.Two examples of push force are as follows:

• A heavy box at rest is pushed to move it from one room to another. This changes the state of motion of the box. A player pushes a football using his foot. This changes the state of motion of the ball

$5$.LED is a semiconductor device which glows even when a week current passes through it. There are two wires called leads attached to an LED. One lead is slightly longer than the other. ... We can also detect weak electric current flowing through a liquid by using a compass .

$\large{\bf{\blue{\underline{\underline{Thanks....!! }}}}}$