Tiêu đề NT 14 PAPER.pdf ✅

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PHYSICS 1. A spherical hole is made in a solid sphere of radius R. The mass of the sphere before hollowing was M. The gravitational field at the centre of the hole due to the remaining mass is: (A) zero (B) 2 GM 8R (C) 2 GM 2R (D) 2 GM R 2. A projectile of mass m is thrown vertically up with an initial velocity v from the surface of earth (mass of earth = M). If it comes to rest at a height h, the change in its potential energy is (A) GMmh/R(R + h) (B) GMmh2 /R(R + h)2 (C) GMmhR /(R + h) (D) GMm/hR(R + h) 3. The minimum projection velocity of a body from the earth's surface so that it becomes the satellite of the earth (Re = 6.4 × 106 m). (A) 11 × 103 ms–1 (B) 8 × 103 ms–1 (C) 6.4 × 103 ms–1 (D) 4 × 103 ms–1 4. Two identical rods in geometry but of different materials having co-efficients of thermal expansion 1 and 2 and Young’s modulli Y1 and Y2 respectively are fixed between two rigid massive walls. The rods are heated such that they undergo the same increase in temperature. There is no bending of the rods. If 1 : 2 = 2 : 6 the thermal stresses developed in the two rods are equal provided Y1 : Y2 is equal to : (A) 2 : 3 (B) 1 : 1 (C) 3 : 1 (D) 4 : 9 5. A 2m long rod of radius 1 cm which is fixed from one end is given a twist of 0.8 radians. The shear strain developed will be :– (A) 0.002 (B) 0.004 (C) 0.008 (D) 0.016 6. A vertical U-tube of uniform inner cross section contains mercury in both sides of its arms. A glycerin (density =1.3g/cm3 ) column of length 10cm is introduced into one of its arms. Oil of density 0.8 gm/cm3 is poured into the other arm until the upper surfaces of the oil and glycerin are in the same horizontal level. Find the length of the oil column, Density of mercury = 13.6 g/cm3 (A) 10.4cm (B) 8.2 cm (C) 7.2cm (D) 9.6cm 7. Density of the ice is  and that of water is . What will be the decreasing volume when a mass M of ice melts : (A)   M – (B)   – M (C)     −     1 1 M (D)     −     1 1 1 M 8. A solid ball of density 1 and radius r falls vertically through a liquid of density 2. Assume that the viscous force acting on the ball is F = krv, where k is a constant and v its velocity. What is the terminal velocity of the ball? (A)   −  2 4 gr ( ) 1 2 3k (B) 2 r( )   −  1 2 3gk (C)   +  1 2 2 2 g( ) 3gr k (D) None of these 9. The pressure just below the meniscus of water - (A) is greater than just above it (B) is lesser than just above it (C) is same as just above it (D) is always equal to atmospheric pressure PW – AITS_NT-14
10. When a capillary is dipped in water, water rises 0.015m in it. If the surface tension of water is 75 × 10–3 N/m, the radius of capillary is- (A) 0.1 mm (B) 0.5 mm (C) 1 mm (D) 2 mm 11. A spherical drop of water has radius 1 mm. If surface tension of water is 70 × 10–3 N/m, difference of pressure between inside and outside of the spherical drop is- (A) 35 N/m2 (B) 70 N/m2 (C) 140 N/m2 (D) zero 12. The variation of density of a solid with temperature is given by the formula - (A) ( ) = +  − 1 2 2 1 d d 1 t t (B) ( ) = −  − 1 2 2 1 d d 1 t t (C) ( ) = −  − 1 2 2 1 d d 1 2 t t (D) ( ) = +  − 1 2 2 1 d d 2 2 t t 13. The densities of wood and benzene at 0°C are 880 kg/m3 and 900 kg/m3 respectively. The coefficients of volume expansion are 1.2 × 10–3 /°C for wood and 1.5 × 10–3 /°C for benzene. At what temperature will a piece of wood just sink in benzene? (A) 80°C (B) 64°C (C) 72°C (D) 83°C 14. A clock which keeps correct time at 20oC has a pendulum rod made of brass. How many seconds will it gain or lose per day when temperature falls to 0oC (  = 18 ×10–6 / oC)? (A) 155.5 s (B) 15.55 s (C) 25.55 s (D) 18.55 s 15. 10 gm of ice at – 20oC is added to 10 gm of water at 50oC. Specific heat of water = 1 cal/g-oC, specific heat of ice = 0.5 cal/gm - oC. Latent heat of ice = 80 cal/gm. Then resulting temperature is- (A) –20oC (B) 15oC (C) 0oC (D) 50oC 16. The graph shows the variation of temperature (T) of one kilogram of a material with the heat (H) supplied to it. At O, the substance is in the solid state. From the graph, we can conclude that - (A) T2 is the melting point of the solid (B) BC represents the change of state from solid to liquid. (C) (H2 – H1) represents the latent heat of fusion of the substance. (D) (H3 – H1) represents the latent heat of vaporization of the liquid. 17. When the temperature of an iron sphere of mass 1kg. falls from 30°C to 25° C, then 550 calories of heat are released. The heat capacity of iron sphere will be in Cal/°C - (A) 110 (B) 220 (C) 330 (D) 440 18. One end of a copper rod of length 1.0 m and area of cross-sector 10–3 m2 is immersed in boiling water and the other end in ice. If the coefficient of thermal conductivity of copper is 92 cal/ms °C and the latent heat of ice is 8 × 104 cal/kg, then the amount of ice which will melt in one minute is - (A) 9.2 × 10–3 kg (B) 8 × 10–3 kg (C) 6.9 × 10–3 kg (D) 5.4 × 10–3 kg 19. Choose the correct statement- (A) Stefan’s law and Newton’s law of cooling both hold true at all the temperature. (B) Stefan’s law holds when the excess of temperature over the surroundings is small, whereas Newton’s law is valid at all the temperature. (C) Newton’s law holds when the excess of temperature over the surroundings is small, whereas Stefan’s law is valid at all temperatures. (D) Excess of temperature over the surroundings should be small for both the laws to hold true.
20. If for a black body the graph of change is emissive power at different temperatures T1, T2 and T3 with wavelength is according to the figure then - (A) T1 = T2 = T3 (B) T3 > T2 > T1 (C) T1 > T2 > T3 (D) T3 > T1 > T2 21. When an ideal diatomic gas is heated at constant pressure , the fraction of the heat energy supplied which increases the internal energy of the gas is . (A) 2 5 (B) 3 5 (C) 3 7 (D) 5 7 22. In an adiabatic process on a gas with  = 1.4, the pressure is increased by 0.5%. The volume decreases by about (A) 0.36% (B) 0.5% (C) 0.7 (D) 1% 23. A Carnot engine works between 600 K and 300 K. In each cycle of operations, the engine draws 1000 joule of energy from the source at 600 K. The efficiency of the engine is - (A) 20% (B) 50% (C) 70% (D) 90% 24. A gas is expanded from volume V0 to 2V0 under three different processes. Process 1 is isobaric process, process 2 is isothermal and process 3 is adiabatic. Let U1,U2 and U3 be the change in internal energy of the gas is these three processes. Then : (A) U1 > U2 > U3 (B) U1 < U2 < U3 (C) U2 < U1 < U3 (D) U2 < U3 < U1 25. Two samples of a gas A and B initially at same temperature and pressure, are compressed to half their initial volume, A isothermally and B adiabatically. The final pressure in - (A) A and B will be same (B) A will be more than in B (C) A will be less than in B (D) A will be double that in B 26. When an ideal gas is compressed isothermally then its pressure increases because: (A) its potential energy decreases (B) its kinetic energy increases and molecules move apart (C) its number of collisions per unit area with walls of container increases (D) molecular energy increases 27. Consider a mixture of oxygen and hydrogen kept at room temperature. As compared to a hydrogen molecule an oxygen molecule hits the wall (A) With greater average speed (B) with smaller average speed (C) with greater average kinetic energy (D) with smaller average kinetic energy. 28. In the following figures (A) to (D), variation of volume by change of pressure is shown. A gas is taken along the path ABCDA. The change in internal energy of the gas will be: (A) (B) (C) (D) (A) positive in all cases from (A) to (D) (B) positive in cases (A), (B) and (C) but zero in case (D) (C) negative in cases (A), (B) and (C) but zero in case (D) (D) zero in all the four cases. E  T1 T2 T3