INDIAN SCHOOL AL WADI AL KABIR

CLASS VIII DEPARTMENT OF SCIENCE -2016-17 NAME

W.S.NO.6 TOPIC- PRESSURE DATE: 21.08.16

1. Name the following

a) The force applied on a surface per unit area.

b)The force exerted by the weight of the atoms over unit area.

c) The S I unit of pressure equal to one Newton per square meter.

d) The force exerted by air, water and other liquids.

e) An instrument used to measure atmospheric pressure.

f) An instrument used to measure liquid pressure.

2. Answer the following questions in a sentence.

a)What is the effect of altitude on atmospheric pressure?

b) How is force related to pressure?

c) What do you understand by the term weight?

3. Give reasons to support your answers.

a) Sharp knives are preferred over blunt knives to cut vegetables in the kitchen.

b) Dams have broader bases.

c) It is very easy for a camel to walk on sand.

d) Skis are used to slide over snow.

e) School bags are provided with broader straps.

4. Answer the following activity based questions:

a) Explain the statement “liquid pressure varies with depth, with the help of an experiment.

b) Write an experiment to show that liquid exerts equal pressure at same depths.

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c) Write the process of construction and working of a U tube manometer.

d) Why do rubber suckers stick strongly when pressed to a very smooth surface?

e) It is said that atmosphere exerts pressure .We do not feel it .Why?

f) While flying in an air plane our ears pop. Why?

Graded Activity F A II Marks 10 (2x5)

Solve the following numericals.

1. If a block weighs 60N and is lying on a side with are 2m by 3m, what is the pressure exerted on the surface?

2. Calculate the force needed to produce a pressure of 2 Pascal’s over a square area of side 4m.

3. A box weighs 400N.Calculate he pressure exerted by the solid on a surface if the area of contact is

200cm2 ?

4. Over what area should a force of 200N act to produce a pressure of 400pascal?

5.If the area of a marble piece weighing 200N is 25m2,how much pressure can it apply when kept on the ground? Page 2 of 2

Prepared by Ms. Rexy N