Question

Air is streaming past a horizontal aeroplane wing such that its speed is 120 m/s over the upper surface and 90 m/s at the lower surface. If the density of air is 1.3 kg/m3, find the difference in pressure between the top and bottom of the wing. If the wing is 10 m long and has an average width 2m, calculate the gross lift of the wing. 

Solution

Correct option is

 

According to Bernoulli’s equation for a horizontal plane, i.e.,

          PE = constant 

           

   

    

                        

  

                               .

SIMILAR QUESTIONS

Q1

When equal volumes of two metals are mixed together, the specific gravity of alloy is 4. When equal masses of the same two metals are mixed together, the specific gravity of the alloy is 3. Calculate the specific gravity of each metal.    

Q2

An open end wide tube is immersed vertically in mercury in such a way that a length 0.05 m extends above the mercury level. The open end of the tube is then closed and the tube is raised further by 0.43 m. Calculate the length of the air column above the mercury level in the tube.

                                                                         

Q3

 

A balloon filled with hydrogen has a volume of 1 m3 and its mass is 1 kg. What would be the volume of block of a very light material which it can just lift?

[Density of material of block is 91.3 kg/m3 and that of air is 1.3 kg/m3]  

Q4

A certain block weighs 15 N in air. It weighs 12 N when immersed in water. When immersed in another liquid, it weighs 13 N? Calculate the relative density of (a) the block (b) the other liquid.

Q5

A piece of copper having an internal cavity weighs 264 g in air and 221 g in water. Find the volume of the cavity. Density of copper is 8.8 g/cc.

Q6

A piece of brass (alloy of copper and zinc) weighs 12.9 g in air. When completely immersed in water it weighs 11.3 g. what is the mass of copper contained in the alloy? Specific gravities of copper and zinc are 8.9 and 7.1 respectively.    

Q7

In English the phrase ‘tip of the iceberg’ is used to mean a small visible fraction of something that is mostly hidden. For a real iceberg what is this fraction if the density of sea water is 1.03 g/cc and that of ice is 0.92 g/cc?

Q8

A piece of metal floats on mercury. The coefficient of volume expansion of the metal and mercury are  respectively. If the temperature of both mercury and metal are increased by an amount , by what factor the fraction of the volume of the metal submerged in mercury changes?

Q9

A block of wood floats in water with two-thirds of its volume submerged. In oil the block floats with 0.90 of its volume submerged. Find the density of (a) wood and (b) oil, if density of water is 103 kg/m3  

Q10

A horizontal pipe line carries water in a streamline flow. At a point along the pipe where the cross-section area is 10 cm2, the water velocity is 1 m/s and the pressure is 2000 Pa. What is the pressure of water at another point where the cross-section area is 5 cm2?