SSC Worksheet for Chapter - 3 Atmospheric Pressure Class 8
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Find SSC Worksheet for chapter-3 Atmospheric Pressure class 8
CLASS-8
BOARD: SSC
Physics Worksheet -3
TOPIC: Atmospheric Pressure
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SCC Worksheet for class 8 Science
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Fill in the blanks :
1. The unit of pressure is _________
2. The unit of force is ________
3. If the area, on which the applied force is acting, decreases, then pressure will ________
4. Knives & blades have sharp edges to increase_______
5. Snow ski-boards are long and broad to _____ the pressure so that they don’t sink into the snow.
6. Ink does not spill out of an ink dropper because pressure due to ink inside and external atmospheric pressure are_____
7. Fluids exert _______ pressure in all directions
8. Keeping the applied force constant, if surface area is doubled, pressure will become_________
9. Fluids flow from a region of _______ pressure to region of ________pressure.
10. Why do school bags have broad shoulder straps?
11. How do we survive despite large atmospheric pressure acting on us?
12. Why do our ears ache while travelling by plane?
13. Explain the blowing of land breeze in a coastal town.
14. Why does cool breeze blow in the beach during afternoons?
15. Explain in brief the principle and working of
(a) Ink dropper
(b) Spray pump.
16. Describe a simple experiment to demonstrate existence of atmospheric pressure.
Solutions: to worksheet-3 Topic- Atmospheric Pressure
Fill in the blanks :
1. Newton per square meter
2. Newton
3. Increase
4. Pressure
5. Reduce
6. Equal
7. Equal
8. Half
9. Higher, lower
10. Pressure is defined as force per unit area. For a constant force if area is increase pressure decreases, so we feel less pain carrying bag which has broad straps [strap area is more]
11. Human being have adapted to atmospheric pressure
Human beings have evolved on earth and adapted to the pressure present on earth, pressure inside body and outside the body are same. If one introduced to the vacuum of space without protection he will swell like over-inflated balloons, ultimately bursting in a gruesome spray of blood.
12. When you experience earaches while in flight, it is called ear barotrauma. Ear barotrauma is the pain and possible damage to the ear related to pressure inequalities between the outside and inside of the eardrum. Flying causes a change in altitude which causes the change in atmospheric pressure.
13.
Land breeze
During the night, the sea water is able to retain its heat better due to its high specific heat capacity, so the air above it is heated up during the night. The warmer air is less dense, so it rises. The air above the land is cooler, (since the land has a lower heat capacity, it loses its heat faster) so the air above the land will now flow towards the sea to form the land breeze.
14.
Cool breeze
is a wind from the sea that develops over land near coasts. It is formed by increasing temperature differences between the land and water (the land gets heated up faster than the sea); these create a pressure minimum over the land due to its relative warmth, and forces higher pressure, cooler air from the sea to move inland.
15.
(a) Ink dropper
Principle:
it works on the principal of air pressure difference.
When we fill ink inside the dropper we have to press its bulb (upper, soft rubber portion), because of Which the air inside the dropper is removed and low air pressure region is formed.
When we dip it in the ink, the space is filled with ink, which remains retained in it unless we press the bulb again.
(b)
Spray Pump
Principle:
When air passes through a region at a large speed, the pressure there decreases.
16. We can demonstrate two simple experiments in order to understand the presence of atmospheric pressure.
Any one experiment can be stated.
Experiment 1
: Take a tin can and heat it with its cork in the open position. The heat will make the air inside hot. The hot air will leave the container. Now quickly close the container. You will notice that the tin can collapses. This is because the air inside the tin container is expelled partially on heating. When you close the container, there is no way for the air outside to enter the tin. The air pressure inside is less than the air pressure outside the tin. The air outside the tin presses against its surface. This crushes the tin. The surface area of the tin is reduced, till such time that the pressure inside becomes same as the pressure outside.
The experiment shows that air exerts pressure.
Experiment 2
: Take a glass and fill it with water up to the brim. No air gap should remain between the water level and the rim of the glass. Cover the glass with a postcard or a cardboard piece. Invert the glass quickly. You will notice that the cardboard and water are held in place. This implies that some force is acting on the cardboard from below, which is able to hold the weight of water on it. The force is the atmospheric pressure acting in the upward direction.
The experiment also shows that air exerts pressure.
