Physics - Study Mode
[#626] A solid needle placed horizontally on the surface of the water floats due to
Correct Answer
(C) Surface tension of water
Explanation
Solution: A solid needle placed horizontally on the surface of water floats due to surface tension of water.
[#627] Purity of a metal can be determined with the help of
Correct Answer
(C) Archimedes principle
Explanation
Solution: Purity of a metal can be determined with the help of Archimedes Principle which makes use of the densities and buoyancy of metals. Finding the density of a metal sample can help to determine its purity. It is most commonly used in the checking the purity of gold.
[#628] Buoyancy depends on
Correct Answer
(A) The mass of the liquid displaced
Explanation
Solution: Buoyancy depends on the mass of the liquid displaced.
[#629] When a steel ball is placed on the surface of mercury, it does not sink because
Correct Answer
(D) The density of mercury is greater than that of steel
Explanation
Solution: When a steel ball is placed on the surface of mercury, it does not sink because the density of mercury is greater than that of steel.
[#630] Clouds float in the atmosphere because of their
Correct Answer
(B) Low density
Explanation
Solution: The key to why clouds float is that the density of the same volume of cloud material is less than the density of the same amount of dry air. Just as oil floats on water because it is less dense, clouds float on air because the moist air in clouds is less dense than dry air.