BUET Admission Test 2008-2009

প্রশ্ন ৯০·সময় ৩ ঘণ্টা

1. A car, sounding a hom of frequency 1000 Hz 1000 \mathrm{~Hz} , is moving directly towards a wall at a speed of 15 ms1 15 \mathrm{~ms}^{-1} . If speed of sound is 340 ms1 340 \mathrm{~ms}^{-1} , then the frequency of the echo heard by the driver is:

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2. Three capacitors 2,3 and 6μF 6 \mu \mathrm{F} are connected in series to a 10 V 10 \mathrm{~V} source. The charge on the 3μF 3 \mu \mathrm{F} capacitor is:

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3. For a certain gas, the ratio of specific heats is given by γ=1.4 \gamma=1.4 . For this gas:

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4. Which of the following is the correct order of acidity?

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5. Read the following pasage and answer the question:

We believe that the earth is about 4.6 billion years old. At present, we are forced to look to other bodies in the solar system for hints as to what the early history of the earth was like. Studies of our Moon, Mercury, Mars and the large satellites of Jupiter and Saturn have provided ample evidence that all these large celestial bodies were bombarded by smaller objects in a wide variety of sizes shortly after the larger bodies have formed. This same bombardment must have affected earth as well. The lunar record indicates that the rate of impacts decreased to its present low level about 4 billion years ago. On erath, subsequent erosion and crustal motions have obliterated the craters that must have formed during this epoch. Scientists estimate the earth's age by measuring the ratios of various radioactive elements in rocks. The oldest earth rocks tested thus far are about 313\mathrm{3\frac{1}{3}} billion years old. But no one knows whether these are oldest rocks on earth. Tests on rocks from the moon and on meteorites show that these are about 4.6 billion years old. Scientists believe that this is the true age of the solar system and probably the true age of the earth.

Which of the follwoing bodies was NOT studied to give evidence that the earth was bombarded in its early history?

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