Q. 84.4( 22 Votes )
Suppose the acceleration due to gravity at a place is 10 m/s2.
Find its value in cm/(minute)2.
1 meter of length contains 100 centimeters i.e. 1m = 100 cm
So 10 meters should contain 10 × 100 cm
10 m = 1000 cm = 103 cm …(i)
1 minute contains 60 seconds so 1 second is of a minute
1 minute = 60 seconds 1 second = minute
(1 second)2 = minute2 = minute2
10 m/s2 =
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In an experiment to estimate the size of a molecule of oleic acid 1 mL of oleic acid is dissolved in 19 mL of alcohol. Then 1 mL of this solution is diluted to 20 mL by adding alcohol. Now 1 drop of this diluted solution is placed on water in a shallow trough. The solution spreads over the surface of water forming one molecule thick layer. Now, lycopodium powder is sprinkled evenly over the film and its diameter is measured. Knowing the volume of the drop and area of the film we can calculate the thickness of the film which will give us the size of oleic acid molecule.
Read the passage carefully and answer the following questions:
(a) Why do we dissolve oleic acid in alcohol?
(b) What is the role of lycopodium powder?
(c) What would be the volume of oleic acid in each mL of solution prepared?
(d) How will you calculate the volume of n drops of this solution of oleic acid?
(e) What will be the volume of oleic acid in one drop of this solution?
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(a) How many astronomical units (A.U.) make 1 parsec?
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(Comment : This is to illustrate why a telescope can magnify planets but not stars.)
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1u = 1.67 × 10-27 kg.
(a) Show that the energy equivalent of 1 u is 931.5 MeV.
(b) A student writes the relation as 1 u = 931.5 MeV. The teacher points out that the relation is dimensionally incorrect. Write the correct relation.
Physics - Exemplar
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