A Vertical U-tube Of Uniform Cross-sectional Area A Contains A Liquid Of Density ρ. The Total Length Of The Liquid Column In The Tube Is L. The Liquid Column Is Disturbed By Gently Blowing Into The Tube. If Viscous Effects Are Neglected, The Time Period Of The Resulting Oscillation Of The Liquid Column Is Given By 

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Question

A vertical U-tube of uniform cross-sectional area A contains a liquid of density ρ. The total length of the liquid column in the tube is L. The liquid column is disturbed by gently blowing into the tube. If viscous effects are neglected, the time period of the resulting oscillation of the liquid column is given by 

Solution

Correct option is

 

Let the liquid in the left arm be depressed by, say, x. The liquid level in the right arm is raised by an equal amount x. when left, the liquid levels will oscillate in each arm about their respective equilibrium position A, A’(see fig). If viscous effects are neglected, the liquid will never come too rest.

Since the column in the right arm is higher by 2x than the column in the left arm, the mass of this column of liquid is m = 2Aρx. The gravitational forcemg of this column provides the restoring force F. Thus 

                               

If L is the total length of the liquid in the U-tube, the total mass M of the oscillating liquid is  

                                

Hence the acceleration of the liquid column is given by

   

                                 

                                 

                                   

Hence the motion is simple harmonic. The time period of the motion is given by 

                     

Note: The period of oscillation is

independent of the density ρ of the

 liquid and the cross-sectional area

A of the U-tube.        

SIMILAR QUESTIONS

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Two identical strings of a stringed  musical instrument are in unison when stretched with the same tension. When the tension in one string is increased by 1%, the musician hears 4 beats per second. What was the frequency of the note when the string were in unison?

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Q3

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Q4

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Q5

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Q6

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Q7

Two springs of force constants k1 and k2 are connected to a mass mplaced on a horizontal frictionless surface as shown in fig (a) and (b). What is the ratio of the time periods of horizontal oscillation in cases (a) and (b) if k1 = k2?

                                                      

Q8

Two springs of force constants k1 and k2 are connected to a mass m as shown in fig (a) and (b). What is the ratio of the time periods of vertical oscillation in cases (a) and (b) if k1 = k2?

                                        

Q9

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Q10

A cylindrical piece of cork of height h and density ρc floats vertically in a liquid of density ρl. The cork is depressed slightly an released. If viscous effects are neglected, the time period of vertical oscillations of the cylinder is given by