Physics - Study Mode

[#381] Which of the following liquids is most viscous?
Correct Answer

(A) Oil

Explanation

Solution: Here oil is the most viscous liquid.

[#382] Small bubbles are perfectly spherical because of
Correct Answer

(D) Surface tension

Explanation

Solution: Surface tension is responsible for the shape of liquid droplets. Although easily deformed, droplets of water tend to be pulled into a spherical shape by the cohesive forces of the surface layer. In the absence of other forces, including gravity, drops of virtually all liquids would be perfectly spherical. The spherical shape minimizes the necessary “wall tension” of the surface layer according to Laplace’s law.

[#383] Pitot tube is used to measure
Correct Answer

(C) Stagnation pressure

Explanation

Solution: Pitot tube is used to measure stagnation pressure.

[#384] A spherical ball made of steel when dropped in mercury container
Correct Answer

(B) Will be on the surface of mercury

Explanation

Solution: The density of steel usually ranges between 7.75 and 8.05 g/cm3 and the density of mercury is 13.534 g/cm3. Mercury is denser than steel this will mean that the buoyant force is large enough to float the steel ball. Different materials usually have different densities, so density is an important concept regarding buoyancy, purity and packaging. Osmium and iridium are the densest known elements at standard conditions for temperature and pressure but not the densest materials. Less dense fluids float on more dense fluids if they do not mix.

[#385] If cream is removed from milk, its density
Correct Answer

(A) Increases

Explanation

Solution: The density of pure fresh milk being on the average 1.032, while the density of fat globules is about 0.86. It follows that the removal of cream will increase the density, while the addition of water will decrease it.