Question

Q.18 Explain why:
a) Porters place a round piece of cloth on their heads when they
carry heavy loads. (1)
b) Snow shoes are more effective for walking on snow than
ordinary shoes. Why? (1)
c) We do not feel the large atmospheric pressure acting on us all
the time.(1)
d) When we release the pressure on the bulb of a dropper water
gets filled in dropper (1)
e) When we throw a ball in the upward direction the speed of the
ball decreases (1)​

Answer 1

Answer:

a) Porters place a round piece of cloth on their head when they carry heavy lods as the round piece of cloth increases the area on which the load is placed. We know that when surface is more than pressure is less. As a result, the pressure on their heads get reduced.

b) Snow shoes have spikes that are more effective for walking on snow than ordinary shoes. These spikes create more friction as compared to ordinary one which is necessary for walking on a slippery surface as snow.

c) The reason we can't feel it is that the air within our bodies (in our lungs and stomachs, for example) is exerting the same pressure outwards, so there's no pressure difference and no need for us to exert any effort.

d) The rise of water in the dropper is due to atmospheric pressure. The rise of water in a dropper is due to atmospheric pressure. When all the air escapes from the nozzle, the atmospheric pressure, which is acting on the water, forces the water to fill the nozzle of the dropper.

e) When we throw a ball upwards, its speed retards gradually. This is because the earth produces a gravitational force which brings down everything that goes up. So when a ball is thrown upward the gravity applies force to bring it down which decreases its speed of going up.

Explanation: