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16.

A particle moves with simple harmonic motion in a straight line, In first   $\tau$   sec. after starting from rest it travels a distance a and in next $\tau$   sec. it travels 2a, in same direction, then

A) amplitude of motion is 3a

B) time period of oscillations is $8\pi$

C) amplitude of motion is 4a

D) time period of oscillations is $6\pi$

17.

An open glass tube is immersed in mercury in such away that a length of 8 cm extends above the mercury level. The open end of the tube is then closed and sealed and the tube is raised vertically up by additional  46 cm. What will be length  of the air column  above the mercury  in the tube now  ? (Atmospheric pressure =76 cm of Hg)

A) 16 cm

B) 22 cm

C) 38 cm

D) 6 cm

18.

One mole of diatomic ideal gas undergoes a cyclic process ABC as shown in figure. The process BC is adiabatic. The temperature at A, B and C are 400K, 800K, and 600K. respectively, Choose the correct statement

A) The change in internal energy in whole cyclic process is 250 R

B) The change in internal energy in the process CA is 700R

C) The change in internal energy in the process AB is -350R

D) The change in internal energy in the process BC is -500R

19.

Three rodes of copper, brass and steel are welded together to form a Y-shaped structure. Area of cross-section of each rod is 4 cm2. End of copper rod is maintained at 100° C whereas ends of brass and steel are kept at 0° C. Lengths of the copper, brass and steel rods are 46,13 and 12 cm respectively, The rods are thermally insulated from surroundings except at ends. Thermal conductivities are 0.92 ,0.26 and 0.12 in CGS units, respectively. Rate of heat flow through copper rod is

A) 1.2 cal/s

B) 2.4 cal/s

C) 4.8 cal/s

D) 6.0 cal/s

20.

There is a circular tube in a vertical plane. Two liquids that do not mix and of densities  d1 and d2  are filled in the tube. Each liquid subtends  900 C  angle at centre. Radius joining  their interface  makes an angle   $\alpha$  with vertical, Ration d1/d2  is

A) $\frac{1+\sin \alpha}{1-\sin \alpha}$

B) $\frac{1+\cos \alpha}{1-\cos \alpha}$

C) $\frac{1+\tan \alpha}{1-\tan \alpha}$

D) $\frac{1+\sin \alpha}{1-\cos \alpha}$

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