#### Important 2mark -chapter 1,2,3

11th Standard

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Physics

Use blue pen Only

Time : 00:50:00 Hrs
Total Marks : 100

Part A

Answer any 50 of the following questions

50 x 2 = 120
1. If humans were to settle on other planets, which of the fundamental quantities will be in trouble? Why?

2. How Physics is related to technology and define technology with respect to Physics.

3. Using a screw gauge the thickness of a wire was measured as Smm. Calculate (i) the fractional error (ii) the percentage error
Given data:
Thickness of the wire (t) = 5mm
Accuracy $\triangle t$= 0.01mm

4. When the planet Jupiter is at a distance of 824.7 million kilometers from the earth. its angular diameter is measured to be 35.72 of arc. Calculate the diameter of Jupiter.

5. In an ocean surveillance system of ship fitted with a (RADAR), the time delay between generation of a radio waves reflected from an enemy ship is observed to be 5.6s. Calculate the distance of the enemy ship from the surveillance ship.

6. Discuss the relation of physics with psychology.

7. Define physical quantity

8. What is meant by Triple point of water? Give its value?

9. Define one astronomical unit.

10. Name the instrument to measure Sub-atomic particles.

11. What is meant by significant figure in a measured quantity?

12. Can a quantity have units but still be dimensionless?

13. State the number of significant figures in the following 0.007

14. State the number of significant figures in the following 5213.0

15. State the number of significant figures in the following 2.65 x 1024m

16. Round off the following numbers as indicated 101.55 x 106 up to 4 digits

17. A new unit of length is chosen such that the speed of light in vacuum is unity. What is the distance between the sun and the earth in terms of the new unit if light takes 8 min and 20 s to cover this distance.

18. State the number of significant figures in 0.2370 m

19. Define a scalar. Give examples

20. What is the difference between velocity and average velocity

21. What is right handed coordinate system?

22. Define the term modulus or magnitude of vector.

23. Find the magnitude of vector 3$\hat { i } -2\hat { j } +\sqrt { 3 } \hat { k }$ ?

24. What are the factors the horizontal range directly depends?

25. Does a scalar quantity depends upon the frame of reference chosen.

26. Distinguish between uniformly accelerated and non-uniformly accelerated motion.

27. Can we use the equations of kinematics to find the height attained by a body projected upward with any velocity.

28. A boy is running on a circular track of radius 50 m. Calculate the displacement of the boy after completing 5 rounds of the track.

29. Two vectors $\vec A$ and $\vec B$ of magnitude 5 units and 7 units make an angle 60° with each other. Find the magnitude of the difference vector $\vec A$$\vec B$ and its direction with respect to the vector $\vec A$.

30. Compare the components of vector equation $\vec F_1+\vec F_2+\vec F_3=\vec F_4$

31. An athlete covers 3 rounds on a circular track of radius 50 m. Calculate the total distance and displacement travelled by him.

32. Write an acceleration in terms of its component? (Or) Show that the acceleration is the second derivative of position vector with respect to time.

33. Draw Position time graph of two objects, A & B moving along a straight line, when their relative velocity is zero.

34. If the instantaneous velocity of a particle is zero, will its instantaneous acceleration be necessarily zero?

35. What are the types of motion?

36. A motorboat is racing towards north at 25 kmh-1 and the water current in that region is 10 kmh-1 in the direction of 60° east of south. Find the resultant velocity of the boat.

37. A bullet fired at an angle of 30° with the horizontal hits the ground 3 km away. By adjusting the angle of projection, can one hope to hit the target 5 km away? Assume that the muzzle speed to be fixed and neglect air resistance

38. A gun is fired from a place which is at distance 1.2 km from a hill. The echo of the sound is heard back at the same place of firing after 8 second. Find the speed of sound.

39. Why do passengers fall in backward direction when a bus suddenly starts moving from the rest position?

40. Define inertia of motion.

41. A person rides a bike with a constant velocity $\overset { \rightarrow }{ v }$ with respect to ground and another biker accelerates with acceleration $\overset { \rightarrow }{ a }$ with respect to ground. Who can apply Newton's second law with respect to a stationary observer on the ground?

42. Why are ball bearings used in machinery?

43. What are the forces acting on the vehicle when it moves in circulated road?

44. Define Impulse.

45. It is easier to roll a barrel than to pull it along the road. Why?

46. What is the need of banking a circular road?

47. Why are wheels of automobiles made circular?

48. A bend in a level road has a radius of 100 mtrs. Find the maximum speed which a car turning this bend may have without skidding, if the coefficient of friction between the tyres and road is 0.8.

49. If a ball is thrown up in a moving train, it comes back to the thrower's hands. Why?

50. Lubricants are used between the two parts of a machine. Why?

51. What provides the centripetal force to a car taking a turn on a level road?

52. A body is acted upon by a number of external forces. Can it remain at rest?

53. China wares are wrapped in straw paper before packing. Why?

54. If a stone of mass 0.25 kg tied to a string executes uniform circular motion with a speed of 2 m s-1 of radius 3 m, what is the magnitude of tensional force acting on the stone?

55. Consider a circular leveled road of radius 10m having coefficient of static friction 0.81. Three cars (A, B and C) are travelling with speed 7 ms-1, 8m s-1 and 10 ms-1 respectively. Which car will skid when it moves in the circular level road? (g = 10 m s-2).

56. A wooden box is lying on an inclined plane. What is the coefficient of friction if the box starts sliding when the angle of inclination is 45°.

57. Three blocks of masses 10 kg, 7 kg and 2 kg are placed in contact with each other on a frictionless table. A force of 50 N is applied on the heaviest mass. What is the acceleration of the system?

58. Find the maximum speed at which a car can turn round a curve of 36 m radius on a level road. Given the coefficient of friction between the tyre and the road is 0.53.