Tiêu đề AITS 02 (1).pdf ✅

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SPACE FOR ROUGH WORK [2] SECTION-I (PHYSICS) SECTION - A 1. A rod of mass m and length l is lying on a horizontal table. Work done in making it stand on one end will be: (1) mgl (2) 2 mgl (3) 4 mgl (4) 2mgl 2. The energy required to accelerate a car from rest to 10 m/s is W. The energy required to accelerate to car from 10 m/s to 20 m/s is: (1) W (2) 2W (3) 3W (4) 4W 3. A particle tied to a string of negligible weight and length L rotated in a horizontal circular path with constant angular momentum having time period T. If the string length is shortened by L/2 while the particle is in motion, the time period is: (1) 4T (2) 2T (3) T/2 (4) T/4 4. A block of mass m is attached to two unstretched springs of spring constant k each, as shown. The block is displaced towards right through a distance x and is released. The speed of the block as it passes through the mean position will be (1) 2 m x k (2) 2k x m (3) m x k (4) 2k x m 5. A force F acting on a body depends on its displacement S as 1/3 . − F S  The power delivered by F will depend on displacement as (1) 2 3 S (2) 5 3 − S (3) 1 2 S (4) S 0 6. ABC is a right angled triangular plate of uniform thickness. The sides are such that AB > BC as shown in figure. I1, I2, I3 are moments of inertia about AB, BC and CA respectively. Then which of the following relations is correct? (1) I1 = I2 = I3 (2) I2 > I1 > I3 (3) I3 > I2 > I1 (4) I3 > I1 > I2
SPACE FOR ROUGH WORK [3] 7. Four identical thin rods each of mass m and length L are joined together to form a square frame. The moment of inertia of this frame about an axis passing through any side of frame is: (1) 2 2 3 mL (2) 2 6 mL (3) 2 5 3 mL (4) 2 6 6 mL 8. If a machine gun fires n bullets per second each with kinetic energy K, then the power of the machine gun is: (1) nK2 (2) K/n (3) n 2K (4) nK 9. A particle moves from position 1 ˆ ˆ ˆ r i j k = + − 3 2 6 to 2 ˆ ˆ ˆ r i j k = + + 14 13 9 under the action of force ˆ ˆ ˆ 4 3 i j k + + N. The work done by this force will be: (1) 100 J (2) 50 J (3) 200 J (4) 75 J 10. A block of mass m is kept on a platform which starts from rest with constant acceleration g/2 upward, as shown in figure. Work done by normal reaction on block in time t is: (1) 2 2 8 −mg t (2) 2 2 8 mg t (3) 0 (4) 2 2 3 8 mg t 11. A force ( ) F i j = − 6 8 ˆ ˆ N acts on a particle and displaces it over 4 m along the x-axis and then displaces it over 6 m along the y-axis. The total work done during these two displacements is: (1) 72 J (2) 24 J (3) –24 J (4) Zero 12. Find the position of center of mass of the uniform lamina radius of a shown in figure. (1) ,0 2   −     a (2) ,0 3   −     a (3) ,0 6   −     a (4) ,0 9   −     a 13. 2 bodies of different masses of 2 kg and 4 kg are moving with velocities 20 m/s and 10 m/s towards each other due to mutual gravitational attraction. What is the velocity of their centre of mass? (1) 5 m/s (2) 6 m/s (3) 8 m/s (4) Zero