G. Give reasons for the following:
1. The atmospheric pressure decreases with increase in altitude.
2. It is easier to open a door with its handle than pushing it near the hinges.
3. Our noses sometimes bleed at high altitudes.
4. The body of a deep water sea fish often bursts when brought to the surface suddenly.
5. Deep sea divers wear a protective suit.
6. Water supply tanks are placed higher than the buildings in a town.
7. It is easier to open a nut by a long spanner.
8. Mercury is used as a barometeric liquid.
9. A bubble is seen to grow in size as it rises to the surface of liquid.
10. It is easier to turn a wheel by its rim than at its centre.
Answers
Answer:
1. Atmospheric pressure decreases with increases in the altitude. As we know that the density of air becomes heavier near the surface of the earth (due to gravity) and begins to lighten as we go to higher altitudes and eventually leads to empty space, i.e. outside the atmosphere of the earth.
2. Larger the distance from the fixed axis or hinge, larger the torque and hence it is easier to open the door.
3. Atmospheric pressure decreases with increase in altitude. Therefore, as we go higher the pressure within the blood vessels exceeds the outside pressure. This causes the blood vessels to rupture. As a result, a mountaineer suffer nose bleeding, ear bleeding etc.
4. The body of the deep sea fish burst when brought up to the surface of the sea water because the body of fish contains dissolved oxygen at much higher pressure than the atmospheric pressure.
5. As pressure at the bottom of the ocean is very high, deep- sea divers wear special diving suits to prevent their bodies from being crushed by the tremendous pressure of water exerted on all sides.
6. The greater the height of the water tank, the more water pressure will be there in the taps of the houses. There is a scientific reason behind placing tanks on high towers. This is because to get the maximum gravitational force so that water flows easily into the pipes.
7. because the longer the spanner is the more is the perpendicular distance between the axis of spanner through which it rotates and the distance of your hand.
8. In the barometer mercury is used as the barometric liquid. Mercury has many advantages when used as a measuring liquid in a barometer tube. Mercury has high density. Because of this property, when there is a change in pressure the change in height of the mercury in the barometer tube will be very reasonable.
9. On the increase of depth, the pressure also increases. Subsequently, when an air bubble rises in water, the pressure decreases. Since the pressure imposed on gas is directly proportional to the volume. Hence, the volume increases and the size of the air bubble rises up in the water.
10. It is easier to turn the steering wheel of a large diameter than that of a small diameter because less force is applied on steering of large diameter which is at a large distance from the centre of rim.