Tiêu đề NT 23 PAPER.pdf ✅

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PHYSICS Section A 1. A and B are two point objects having mass 15 gram and 10 gram respectively located at a distance 50 cm from each other than centre of mass is at (A) 30 cm from B (B) 36 cm from A (C) 30 cm from B (D) 36 cm from B 2. T be the time period of a planet going around the sun along elliptical path having semi- major axis a. Which of the following is correct (A) T 2  a (B) T 2  a 3 (C) T  a 3 (D) T 2  a 2/3 3. A bullet enters into a slab of thickness 20 cm with velocity 200 ms–1 . Inside the slab retardation of the bullet assumed to be constant, it's velocity decreases by 20% till it crosses the slab. Time taken by the bullet to cross the slab nearly equals to (A) 1.1 × 10–3 s (B) 1.6 × 10–3 s (C) 2.6 × 10–3 s (D) 3.2 × 10–3 s 4. In the situation shown acceleration of the blocks will be 6 kg 4kg  = 0.4 (A) 1.6 ms–2 (B) 2.4 ms–2 (C) 3.2 ms–2 (D) 4 ms–2 5. A simple pendulum consists of an inextensible string of length L and a suspended mass M. At the instant the mass crosses the equilibrium position with velocity V, tension in the string of the pendulum is (A) T = MV 2 L (B) T = Mg (C) T = Mg + MV 2 L (D) T = Mg – MV 2 L 6. A load of mass 500 kg is suspended by a metal wire having cross sectional area 2 5 mm . Stress produced in the wire is (A) 6 2 10 Nm− (B) 9 2 10 Nm− (C) 3 2 10 Nm− (D) 8 2 10 Nm− 7. Which of the following can be obtained, from the ratio of maximum acceleration to maximum velocity in a SHM? (A) Time period (B) Frequency (C) Angular frequency (D) All of the these 8. In the situation shown a man of mass 60 kg is initially located at the left end of 8 m long trolley of mass 240 kg. The system is initially at rest over a smooth horizontal surface. The man walks to reach the right and of the trolley, at rest over a smooth horizontal surface. The man walks to reach the right end of the trolley, displacement of the trolley will be – Smooth (A) 2 m (B) 1.6 m (C) 2.4 m (D) zero 9. Disc A (M, R) and Disc B (3M, 2R) are combined as shown in the figure. Moment of inertia of the combination about common diametrical axis can be given by axis B A (A) 13 2 MR 2 (B) 13 2 MR 4 (C) 11 2 MR 2 (D) 11 2 MR 4 PW – AITS_NT-23
10. A particle is moving along a straight line with increasing speed. Its angular momentum about a fixed point on this line (A) Goes on increasing (B) Goes on decreasing (C) May be increasing or decreasing depending on direction of motion (D) Remains zero 11. A disc of mass M kg and radius R meter is rotating at an angular speed  rad/s when the motor is switched off. Neglecting the friction at the axle, the force that must be applied tangentially to the wheel to bring it to rest in time t is (A) MR 2t  (B) MR t  (C) 2MR t  (D) 2 MR 2t  12. Two waves having intensity I0 and 2I0 interfere with a phase difference /4 radian. Intensity of resultant wave will be (A) I0 (3 + 2√2) (B) I0 (2 + 3√2) (C) 3I0 (D) 5I0 13. A source of sound emitting frequency 620 Hz approaches a stationary listener with velocity 30 ms-1 . Frequency received by the listener is 680 Hz. Velocity of sound is equal to (A) 336 ms-1 (B) 340 ms-1 (C) 342 ms-1 (D) 320 ms-1 14. A position dependent force is given by F = cx2 where F is in Newton and x is in metre and C = 0.2 Nm-2 . During displacement from x = – 1m to x = 2m work performed by the force will be (A) 0.2 J (B) 0.3 J (C) 0.5 J (D) 0.6 J 15. Potential energy as function of position is given by U = ax – bx2 (a, b > 0) Position and type of equilibrium is (A) a x 2b = , stable (B) a x 2b = , unstable (C) 2a x b = ,neutral (D) a x 2b =− , stable 16. If the mean free path of atoms is doubled then the pressure of gas will become (A) P/4 (B) P/2 (C) P/8 (D) P 17. Shearing strain is expressed by (A) Angle of shear (B) Angle of twist (C) Decreases in volume (D) Increase in volume 18. A bar of iron is 10 cm at 20°C. At 19°C it will be (Fe = 11 × 10-6 /°C) (A) 11 × 10-6 cm longer (B) 11 × 10-6 cm shorter (C) 11 × 10-5 cm shorter (D) 11 × 10-5 cm longer 19. In a given process for an ideal gas, W = 0 and Q < 0. Then for the gas (A) The temperature will decrease (B) The volume will increase (C) The pressure will remain constant (D) The temperature will increase 20. If 10000 cal of heat is added to 4 mole of a monoatomic gas without changing its volume, then change in temperature of the gas is (A) 233 K (B) 833 K (C) 123 K (D) 433 K 21. A wire PQRST carrying current I = 5A is placed in uniform magnetic field B = 2T as shown in fig. If the length of part QR = 4cm and SR = 6 cm then the magnetic force on SR edge of the wire is:- a T R B=2T P S Q I=5A (A) 0.4 N (B) 0.6 N (C) Zero (D) 6 N
22. A block of mass m & charge q is released on a long smooth inclined plane magnetic field B is constant, uniform, horizontal and parallel to surface as shown. Find the time from start when block loses contact with the surface (A) m cos θ qB (B) m cose cθ qB (C) m cot θ qB (D) None 23. A particle has mass m0 and charge q0 when it is at rest. The same particle has mass m and charge q when it is moving with v = c/2, where c is the speed of light through vacuum, then (A) m = m0 (B) q = q0 (C) q > q0 (D) m < m0 24. direction of propagation of an electromagnetic wave consisting of electric field E⃗ and magnetic field B⃗ is parallel to (A) B⃗ × E⃗ (B) B⃗ − E⃗ (C) E⃗ − B⃗ (D) E⃗ × B⃗ 25. Potential difference between centre and the surface of sphere of radius R and having uniform volume charge density  within it will be : (A) 2 0 R 6   (B) 2 0 R 4   (C) 0 (D) 2 0 R 2   26. A charge q is going around a circle of radius r with constant speed v. Equivalent current due to the circulating charge is given by (A) eq I qv = (B) eq qv I 2 r =  (C) eq qv I 2r  = (D) eq qv I r = 27. Given specific heat of water Sw = 4200 J/kg°C. 500 gram of water is heated by a heated having resistance 84 through which current is 5A. Rise in temperature in 1minute time will be (A) 80°C (B) 60°C (C) 30°C (D)20°C 28. Which of the following statements is wrong for a practical voltmeter (A) Voltmeter is connected in parallel (B) Voltmeter has small resistance (C) Voltmeter is applied to measure potential difference (D) Voltmeter draws current from the circuit. 29. If the speed of orbiting electron in the ground state of H-atom is V0/137, Then the corresponding speed in the ground state of Li++ ion will be (A) v = 9c 137 (B) v = 3c 137 (C) v = c 3×137 (D) v = c 137 30. Work function of molybdenum (M0) is nearly 4.17 eV. Corresponding threshold frequency (0) is close to (A) 8 × 1014 Hz (B) 1 × 1015 Hz (C) 1.5 × 1015 Hz (D) 2.4 × 1015 Hz 31. A Particle of mass 1 mg is moving with velocity 5 cm/s. de-Broglie wavelength associated with the particle is equal to (A) 1.72 × 10–25 m (B) 1.32 × 10–29 m (C) 1.32 × 10–26 m (D) 1.24 × 10–26 m B • m 