Question

 

If a room has dimensions , what is the mass of air in the room if density of air at NTP is 1.3 kg/m3?

[Density of water is 103 kg/m3 and g = 10 m/s2]

Solution

Correct option is

78 kg

 

As density is defined as the ratio of mass to volume, i.e.,

            

           

               

                = 78 kg. 

i.e., mass of air in the room is 78 kg which is unbelievable (as air is assumed to be weightless) but is true.

SIMILAR QUESTIONS

Q1

 

If the temperature of the air does not vary, the ratio of its pressure to its density is almost constant. In this case. 

         

Where P0 and  are the pressure and density of air, respectively at sea level. Show that with this approximation, the variation of air pressure with altitude y is given by   

         

Q2

An equation for the speed of the liquid as a function of the distance it has fallen

Q3

Combining the above result with the equation of continuity the expression for the red us of the stream as a function of y is 

Q4

If water flows out of vertical pipe at a speed of 1.2 m/s, how far below the outlet will the radius be half the original radius of the stream?

Q5

A 60 kg swimmer pulls himself into a  raft moored in the meddle of a small lake. By how much does the raft sink when the swimmer climds onto it?

Q6

A clever student needs to determine the density of liquid X. She has at her disposal a spring balance and an irregularly shaped object of unknown material that is inert in air, water liquid X. In air the object weighs 2.00N. In water it weighs 1.60N. And in liquid X it weighs 1.70N. The density of liquid X is

Q7

A layer of oil deep floats on a layer of water that is 8 meets deep. The density of the oil is 300 kg/m3. A cube with a volume of 2 m3 floats at the oil-water interface with exactly half of its volume in the water. What is the density of the cube?   

Q8

A barge filled with garbage has a density of 800 kg/m3. What present of the barge’s volume is above the water line? The volume below the water line is called the draft of the ship.    

Q9

A king order for a gold crown having a mass of 2 kg. When it arrives from the goldsmith, the volume of the crown is found to be 200 cm3. What is your opinion about the crown if the density of the pure gold is ? 

Q10

What force  does water exert on the base of a house tank of base area 1.5 m2 when it is filled with water up to a height of 1 m? [Density of water is 103 kg/m3 and g = 10 m/s2