Physics - Study Mode

[#921] At hill stations, the boiling point of water will be
Correct Answer

(B) Less than that at sea level

Explanation

Solution: The boiling point is the temperature at which the vapour pressure of the liquid equals the environmental pressure surrounding the liquid. Atmospheric pressure is due to air above any given point. The atmospheric pressure at high altitudes like hill station is less than at the sea level.Thus, vapour pressure will equal atmospheric pressure at a comparatively low temperature. Thus, the boiling point of water is reduced less than at sea level.

[#922] Instrument used to measure the force and velocity of the wind is
Correct Answer

(B) Anemometer

Explanation

Solution: An anemometer is a device used for measuring wind speed and direction. It is also a common weather station instrument.

[#923] When pressure is increased the melting point of ice
Correct Answer

(C) Decreases

Explanation

Solution: The melting point of ice decreases when pressure increases because when pressure is increased volume is decreased and volume of water is less than ice.

[#924] The wall of a dam is made thicker at the bottom than at the top because the pressure exerted by the water on the wall
Correct Answer

(C) Increases with depth of the wall

Explanation

Solution: The pressure applied to walls of the dam will be a function of the amount of water that is over that particular point on the wall. So water pressure is very large at the bottom due to its large depth. That's why dams are constructed thicker at their bottoms than at their tops.

[#925] What is the change in the angular momentum of a system as per the Law of Conservation of Angular momentum, if the total external torque acting is zero?
Correct Answer

(A) Remains constant

Explanation

Solution: If net external torque on a system is zero, then the angular momentum of the system can not change. If net external torque on a system is zero, then the angular momentum of the system remains same.