CBSE Guess > Papers > Important Questions > Class XII > 2010 > Physics > Physics By Ajay Yadav CBSE CLASS XII
Q. 1. A body covered a distance of l metres along a semicircular path . calculate the magnitude of displacement of the body and the ratio of distance to displacement .[ π/2] Q. 2. a ball dropped from the top of a tower of height h . it covers a distance h/2 in the last second of its motion . how long does the ball remain in air ? g=10m/s2 [(2 ± √2 ) s ] Q. 3. the maximum height attained by a projectile is increased by 10% by increasing its speed of projectile , without changing the angle of projection . what will the percentage increase in the horizontal range .[10%] Q. 4. two trains are headed towards each other on the same track , each having a speed of 30 Km/h . a bird that can fly at 60 km/h flies off one train when they are 60 km apart and leads directly for the other train . on Reaching the other train . on reaching the other train , it flies back ti the first train and so on . (a) how many trips can the bird make from one train to the other before they meet ? (b) what is the total distance the bird travels ? [infinite, 60 km ] Q. 5. a body of mass m is projected with velocity v at an angle of 450 with the horizontal . find the change in its momentum at the end of flight . [√2 mv ] Q. 6. a 100 m sprinter increases her speed from rest uniformly at the rate of 1.5 m/s2 up to three quartera of the total run and covers the last quarter with uniform speed . how much time does she takes to cover the first half and second half of the run ? Q. 7. (a) show that for a projectile the angle between the velocity and the x-axis as function of time is given by Ɵ(t) =tan-1[(voy – gt)/vox], where the various symbols have their usual meanings . (c)show that projectile angle Ɵo for a projectile launched from the origin is given by Ɵo = tan-1[4hm/R] Q. 8. a jet airplane travelling at the speed of 500 km/h ejects its products of combustion at the speed of 1500 km/h relative to thhe jet plane . what is the speed of the later with respect to observer on the ground .[-1000 km/h] Q. 9. a car moving along a straight highway with speed of 126 km/h is brought to stop within a distance of 200 m . what is the retardation of the car and how long does it take for the car to stop ? [11.43 s] Q. 10. a ball is dropped from a height of 90 m on afloor . at each collision with the floor , the ball loses one tenth of its speed . plot the speed –time graph of its motion between t=0 to 12 s . [g=10m/s2] Q. 11. rain is falling vertically with a speed of 30 m/s . a woman rides a bicycle with a speed of 10 m/s in the north to south direction . what is the direction in which she should hold her umbrella ? [ tan18026’] Q. 12. the celling of a long hall is 25 m high . what is the maximum horizontal distance that a ball thrown with a speed of 40 m/s can go without hitting the celling of the hall ? [150.5 m] Q. 13. a man is 16 m behind a bus when it starts acceleration at 2 m/s2 . what is the timetaken by him to board the bus ? [ 4 sec.] Q. 14. a stone tied to the end of a string 80 cm long is whirled in a horizontal circle with a constant speed . if the stone makes 14 revolutions in 25 seconds , what is the magnitude and direction of acceleration of the stone ? [ 9.90 m/s2] Q. 14. two particles A and B are connected by a rigid rod AB . the rod slides along perpendicular rails as shown . velocity of A to the left is 10 m/s . what is the velocity of B when angle α=300 [ 17.32 m/s ] Q. 15. a cyclist is riding with a speed of 27 km/h . as he approaches a circlular turn on the road of radius 80 m , he applies brakes and reduces his speed at the constant rate of 0.5 m/s2 . what is the magnitude and direction of the net acceleration of the cyclist on the circular turn ?[0.86 m/s2 ] Q. 16. a balloon is ascending at 12 m/s . a packet is dropped from it when it is at a height of 65 m from the ground . what is the time taken by the packet to reach ground ? [ 5 sec ] Q. 17. a ball is dropped from a height. If it takes 0.200 s to cross the last 6.00 m before hitting the ground , find the height from which it was dropped . take g=10m/s2. [48 m ] Q. 18. two trains A and B of length 400m each moving on two parallel tracks with a uniform speed of 72 km/h in same direction , with A ahead of B . the driver of B decides to over take A and accelerates by 1 m/s2 . if after 50 s , the guard of b decides to over take A and accelerates by 1 m/s2 . if after 50 s , the guard of B just past the driver of A , what was the original distance between them . [1250 m ] Q. 19. person is standing on a truck moving with a constant velocity of 14.7 m/s on a horizontal road . the man throws a ball in such a way that it returns to the truck after the truck has moved 58.8 m . find the speed and the angle of projection (a) as seen from the truck (b) as seen from the road [19.6 m/s upward, 24.5 m/s at 530 horizontal ]
Paper By Mr. Ajay Yadav |
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