اختبار الفصل الثاني في مادة الانجليزية للثانية ثانوي

size=18]Stream: Second Year (S.E/ M.T)

The Property of Buoyancy

PART ONE/ READING AND INTERPRETING
Everyone knows that some objects float in water and that others do not. An object that floats in water might sink in alcohol, and one that sinks in alcohol might float in glycerine.
All liquids possess in varying degrees the property that is called buoyancy- an upward push upon objects that are submerged. If you throw a piece of dry wood into a pond or a pool, the wood floats, the upward push of the water makes this possible. An object that sinks in water, like a piece of iron, weighs less when under water than in air; this also is because the water exerts an upward pressure upon it.
In the third century B.C., the Greek mathematician and physicist Archimedes discovered the principle of buoyancy, which bears his name. Archimedes’ principle states that the body wholly or partly immersed in the liquid is buoyed upward with a force equal to the weight of the volume of liquid it displaces.

( From The Book of Popular Science, v.2; p32)

A/ Comprehension and interpretation
1) Are there any negative sentences in the above passage? If yes, how many?

2) Say whether the following statements are true or false.
a) The objects that float in water do float in all liquids.
b) Wood doesn’t sink in water.
c) The weight of iron in air is less than under water.
d) If you throw a piece of wet wood into a pond, it floats.
3)
Answer the following questions according to the text.
a) Do all objects float in water?
b) What is the Principle of Buoyancy?

4) Match each idea with its corresponding paragraph.

Ideas Paragraphs
a) Not all objects float in water. 1
b) Water exerts an upward pressure on objects. 2
c) When objects are immersed in a liquid, they displace part of it. 3
5) What do the underlined words in the text refer to?
It (§2) his (§3)

B/ TEXT EXPLORATION
1) Find in the text words that are opposites to the following:
*float (§1) *more(§2)

2) Correct the mistake in each of the following sentences.
a) The property of Buoyancy discovered by Archimedes.
b) All liquids have possess in varying degrees the property of buoyancy.




3) Write sentence (b) so that it means the same as sentence (a).
a) The Principle of Buoyancy was discovered by Archimedes.
b) Archimedes--------------------------------------------------------------------------------------------------------

a) Iron does not float in water.
b) If you throw a piece of iron in water, it (not float).

4) Reorder the following sentences so as to get a coherent paragraph. One sentence is irrelevant.

a) Archimedes was taking his bath in a well-filled tub
b) the weight of the displaced water equals the weight of the block of wood
c) if a block of wood is
d) the displaced water flows into the container at the side of the overflow can
e) put into an overflow can with water


PART TWO/ WRITING
Choose only one topic.
Topic 1: You are caught in a dilemma. Write a letter to an “Agony Aunt” in which you expose your problem and ask for advice.

Topic 2: Some say that great discoveries are made by accident and give the example of Archimedes Principle of Buoyancy.
Write a short paragraph in which you disagree with this idea. Use the following notes:

*chance alone is not enough
*only people of genius can observe phenomena
*it takes a genius to understand the accident happening in front of your eyes
*It takes a lifetime of work to make an invention.

Good Luck
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