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#### Important questions

11th Standard

Reg.No. :
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Physics

Use blue pen Only

Time : 01:30:00 Hrs
Total Marks : 90

Part A

11 x 1 = 11
1. How many um present in one metre?

(a)

10-6 $\mu$ m

(b)

106 $\mu$ m

(c)

10-3 $\mu$ m

(d)

10-2 $\mu$ m

2. Identify the pair of physical quantities having the same dimensions.

(a)

Light year and period of a pendulum

(b)

Angular momentum and torque

(c)

Energy and Modulus of elasticity

(d)

Torque and work

3. Which one of the following satatement is true?

(a)

A scalar quantity is conserved in a process

(b)

A scalar quantity does not vary from one point to another in apace

(c)

A scalar quantity can never take -ve values

(d)

A scalar quantity has only magnitude and no direction.

4. Which of the following is true regarding projectile motion?

(a)

horizontal velocity of projectile is constant

(b)

vertical velocity of projectile is constant

(c)

acceleration is not constant

(d)

momentum is constant

5. If a person moving from pole to equator, the centrifugal force acting on him

(a)

increases

(b)

decreases

(c)

remains the same

(d)

increases and then decreases

6. The force F acting on a particle of mass m is indicated by the force-time graph shown below. The change in momentum of the particle over the time interval from zero to 8 s is

(a)

24 N s

(b)

20 N s

(c)

12 N s

(d)

6 N s

7. The work done by the conservative force for a closed path is

(a)

always negative

(b)

zero

(c)

always positive

(d)

not defined

8. The body must have a speed at highest point in vertical circular motion to stay in the circular path

(a)

$\ge \sqrt { gr }$

(b)

$\ge \sqrt { 2gr }$

(c)

$\ge \sqrt { 5gr }$

(d)

$\ge$5gr

9. The angular momentum of a rotating body is doubled, its K.E. of rotation becomes

(a)

Two times

(b)

Four times

(c)

Halved

(d)

Eight times

10. The ratio of the acceleration for a solid sphere (mass m and radius R) rolling down an incline of angle $\theta$ without slipping and slipping down the incline without rolling is,

(a)

5 : 7

(b)

2: 3

(c)

2: 5

(d)

7: 5

11. The gravitational potential energy of the Moon with respect to Earth is

(a)

always positive

(b)

always negative

(c)

can be positive or negative

(d)

always zero

12. Part B

11 x 2 = 22
13. Round off the following numbers as indicated 18.35 up to 3 digits

14. When the planet Jupiter is at a distance of 824. 7 million Ian from the earth, its angular diameter is measured to be 35.72" of arc. Calculate diameter of Jupiter.

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

16. A train 100 m long is moving with a speed of 60 km h-1. In how many seconds will it cross a bridge of 1 km long?

17. "Jumping on a cemented floor receives more injuries than on the sand" - Given reason.

18. Consider two objects of masses 5 kg and 20 kg which are initially at rest. A force 100 N is applied on the two objects for 5 second.
(a) What is the momentum gained by each object after 5s?
(b) What is the speed gained by each object after 5s?

19. Is whole of the kinetic energy lost in any perfectly inelastic collision?

20. What happens to the P.E. of a bubble when it rises in water?

21. A thin metal hoop of radius 0.25m and mass 2 kg starts from rest and rolls down an inclined plane. If its linear velocity on reaching the foot of the plane is 2 ms-1, what is its rotational K.E.at that instant?

22. Some heavy boxes are to be loaded along with some empty boxes on a cart. Which boxes should be put on the cart first and why?

23. Earth revolves around the Sun at 30 km s−1. Calculate the kinetic energy of the Earth. In the previous example you calculated the potential energy of the Earth. What is the total energy of the Earth in that case? Is the total energy positive? Give reasons.

24. Part C

11 x 3 = 33
25. Two resistances RI = (100 ± 3) $\Omega$, R2 = (150 ± 2)$\Omega$, are connected in series. What is their equivalent resistance?

26. The vernier scale of a travelling microscope has 50 divisions which coincide with 49 main scale divisions. If each main scale division is 0.5 mm. Calculate the minimum inaccuracy in the measurement of distance.

27. Define average velocity and represent it graphically.

28. What are positive and negative acceleration in straight line motion?

29. Briefly explain on Aristotle vs. Newton's approach on sliding object.

30. For the following situation, Explain with an example.

31. A body of mass 0.3 kg is taken up an inclined plane of length 10 m and height 5 m and then allowed to slide down to bottom again. Find
(i) work done by frictional force over the round trip if $\mu$ = 0.15.
(ii) kinetic energy at the end of the trip.

32. An elevator which can carry a maximum load of 1800 kg (elevator + passengers) is moving up at a constant speed of 2 ms-1. The frictional force opposing the motion is 4000 N. Determine the minimum power delivered by the motor to the elevator in watts as well as in horsepower.

33. There is a stick half of which is wooden and half is of steel. (i) it is pivoted at the wooden end and a force is applied at the steel end at right angle to its length (ii) it is pivoted at the steel end and the same force is applied at the wooden end. In which case is the angular acceleration more and why?

34. A thin horizontal circular disc is rotating about a vertical axis passing through its center. An insect goes from A to point B along its diameter as shown in Figure. Discuss how the angular speed of the circular disc changes?

35. What are geostationary and polar satellites?

36. Part D

5 x 5 = 25
37. If the value of universal gravitational constant in SI is 6.6$\times$10-11 Nm-2 kg-2,then find its value in CGS System.

38. Calculate the average velocity of the particle whose position vector changes from $\overrightarrow { { r }_{ 1 } } =5\hat { i } +6\hat { j }$ to $\overrightarrow { { r }_{ 2 } } =2\hat { i } +3\hat { j }$  in a time 5 second.

39. What is the reading shown in spring balance?

40. A ball falls under gravity from a height of 10m with an initial downward velocity u. It collides with the ground, loses 50% of its energy in collision and then rises back to the same -'height. Find the initial velocity "u".

41. From a complete ring of mass M and radius R, a sector angle $\theta$ is removed. What is the moment of inertia of the incomplete ring about axis passing through the center of the ring and perpendicular to the plane of the ring?