Question

Answer the following questions:

1. What is friction? What are the two important properties of friction?

2. Mention two simple methods for reducing friction.

3. Draw the structure of Eye and label its parts.

4. What are the characteristics of a good fuel?

5. Why are gold and silver suitable for making jewellery?

6. Explain the different zones of candle flame with a neat labelled diagram​

Answer 1

Answer:

1. Friction is the resistance to motion of one object moving relative to another.

important properties are:

i) It always acts in the direction opposite to the direction of motion.

ii) It's magnitude is equal to that of the force trying to set the object in motion only until it starts to move.

2. two simple methods of reducing friction are:

i) Friction can be reduced by making the surface smooth by polishing.

ii) Friction can be reduced by using ball bearing between the moving parts of machine.

4. The characteristics of a good fuel are:

i) It should possess high calorific value.

ii) It should have proper ignition temperature. The ignition temperature of the fuel should neither be too low nor too high.

iii) It should not produce poisonous products during combustion. In other words, it should not cause pollution o combustion.

iv) It should have low moisture content.

v) it should be cheap.

5.gold and silver are suitable for making jewellery, because:

i) They are highly lustrous metals which are resistant to corrosion.

ii) They are highly malleable and ductile so can be transformed into any shape or design.