Question

Give reason for the following-

a) Why doctors advice to put strips of wet cloth on the forehead of a patient having high fever.

b) A certain amount of water placed on a dish evaporates faster than in a bottle.

c) Ice bergs are dangerous for ships.

d) Why it is easier to open the door by pushing it at its free end.

Answer 1

1. Wet strips absorbs heat from the body and decrease the temperature of the body. this process is called evaporation. Hence to reduce the body temperature doctors advice to put strips of wet cloth on the forehead of a person having high fever.

2. Water in a dish evaporates more quickly than in a bottle bcz surface area of the water spread on dish is more than that of water kept in bottle. rate of evaporation is directly proportional to surface area of water.

3. Icebergs are dangerous because they are huge and they float low in the water which can cause danger to the ships. They tend to flip over at times. When they flip over the energy is so great it can cause tsunamis and on occasion can trigger earthquakes.

4. It is so as the perpendicular distance from the hinges of the door is maximum so less force is required