Physics - Study Mode

[#1351] The force exerted by a magnet is an example of ________
Correct Answer

(A) Non-contact force

Explanation

Solution: The force exerted by a magnet is an example of Non-contact force.

[#1352] A man standing close to the platform at a railway station experiences a pulling force towards a fast moving train because of ________ .
Correct Answer

(D) Pressure difference due to fast moving air in between

Explanation

Solution: When a fast-moving train passes a man standing on the platform at rest, the air between train and person also moves with greater speed. This rapidly moving air, by Bernoulli's principle will have a lower pressure than the still air a few feet away.

[#1353] Which of the following is a result of Surface tension ?
Correct Answer

(C) Capillary action

Explanation

Solution: Capillary action is the result of adhesion and surface tension. Adhesion of water to the walls of a vessel will cause an upward force on the liquid at the edges and result in a meniscus which turns upward. The surface tension acts to hold the surface intact, so instead of just the edges moving upward, the whole liquid surface is dragged upward.

[#1354] A liquid disturbed by stirring comes to rest due to
Correct Answer

(C) Viscosity

Explanation

Solution: A liquid disturbed by stirring comes to rest due to viscosity.

[#1355] A capillary tube is partially dipped vertically in a vessel containing water. Due to capillarity water rises in the tube. The height of water rise in the tube can be increased by
Correct Answer

(A) Decreasing the radius of the capillary tube

Explanation

Solution: The water rise in a capillary tube dipped in water is such that the weight of water in the tube above the surface of water in the vessel is equal to (balances) the upward force due to surface tension. So it is clear that if the the bore (radius) to the tube is decreased, the height of the water column in it must be greater. So, (a) is correct