Second term second test
Read the following text carefully and do the activities.
In the third century B.C., the Greek mathematician and physicist Archimedes discovered the principle of buoyancy. Everyone knows that some objects float in water and others do not. An object that floats in water might sink in alcohol, and one that sinks in water might float in glycerin. All liquids possess the property that is called buoyancy- an upward push upon objects that are submerged within them.
If you throw a piece of wood into a pool, the wood floats; the upward push of water makes this possible. An object that sinks in water – like a piece of metal – weighs less when under water. When you take a bath in a well-filled tub, you can raise your whole body easily. But you could not do this so easily if you tried to raise yourself from an empty one because, though air is buoyant, it is less buoyant than water.
[Adapted The Book of Popular Science, v.2; p.32]
1. Give the general idea of the text. (2 pts)
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2. Answer the following questions according to the text. (4 pts)
a) Why do some objects float in water and others do not?
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b) When did Archimedes discover the principle of buoyancy?
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c) What is the principle of buoyancy?
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d) Is air buoyant?
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3. Who/what do the underlined words refer to in the text? (4 pts)
others (§1)…….…………... one (§1)………………. one (§1)……………..…. It (§1)………..…………..
4. Give the correct form of the verbs in brackets. (4 pts)
When we (to place) an iron ball that weighs ten pounds when weighed in air, we (to discover) that under water this ball (to weigh) only eight pounds and the volume of water that spilled over weighs two pounds, which equals the ball’s loss of weight because the ball (to buoy) by a force- that of buoyancy.
1-.....................................2-......................................3-...................................4-............................................
5. Classify the following words according to the number of their syllables: (4 pts)
buoyancy - physicist - water - mathematics - Archimedes – alcohol – physics
4 syllables 3 syllables 2 syllables
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6. Re-order the following words to make a meaningful sentence: (2 pts)
bath - discovered - Archimedes - a - when - having - the - principle - of - he - buoyancy - was