#### Important 1mark

11th Standard

Reg.No. :
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Physics

Use blue pen Only

Time : 00:30:00 Hrs
Total Marks : 55

Part A

55 x 1 = 55
1. If $\pi=3.14,$ then the value of ${\pi}^{2}$ is

(a)

9.8596

(b)

9.860

(c)

9.86

(d)

9.9

2. The velocity of a particle v at an instant t is given by v = at + br2. The dimensions of b is

(a)

[L]

(b)

[LT-1]

(c)

[LT-2]

(d)

[LT-3]

3. If force |F|, velocity I'VI and time |T| are taken as to fundamental units then the dimensions of mass are

(a)

FV-1T

(b)

FV-1T

(c)

FVT-1

(d)

FVT-2

4. The speed of an object v = 90km/h. The same quantity of speed in m/s is

(a)

90

(b)

25

(c)

45

(d)

180

5. The mass of an iron sheet is 0.250 kg and volume of the sheet is 1.5m3 Then what is the density of the iron sheet? Express the result in SI unit system.

(a)

0.267kg m-3

(b)

0.167 kg m-3

(c)

0.255 kg m-3

(d)

0.285 kg m-3

6. The value of one Angstrom is

(a)

1010m

(b)

10-10m

(c)

10-8m

(d)

10-15m

7. While measuring acceleration due to gravity, by a simple pendulum, a student makes a positive error of 1% in the length of the pendulum and a negative error , of 3% in the value of time period. The percentage error in the measurement of 'g' is

(a)

2%

(b)

4%

(c)

10%

(d)

7%

8. The shift in the position of an object when viewed with two eyes, keeping one eye closed at a time is known as___________.

(a)

basis

(b)

fundamental

(c)

parallax

(d)

pendulum

9. The dimensional formula for heat capacity__________________

(a)

[ML2T2]

(b)

[M L2 K-1]

(c)

[M L2 T2 K-1]

(d)

[M L2 T2 K-1]

10. In a vernier caliper, n divisions of vernier scale coincides with (n - 1) divisions of main scale. The least count of the instrument is ______________

(a)

${1\over n}MSD$

(b)

${n\over n+1}MSD$

(c)

${ n+1\over n}MSD$

(d)

${ n+1\over n-1}MSD$

11. Which one of the following Cartesian coordinate systems is not followed in physics?

(a)

(b)

(c)

(d)

12. Two objects of masses m1 and m2 fall from the heights h1 and h2 respectively. The ratio of the magnitude of their momenta when they hit the ground is

(a)

$\sqrt { \frac { { h }_{ 1 } }{ { h }_{ 2 } } }$

(b)

$\sqrt { \frac { { { m }_{ 1 }h }_{ 1 } }{ { { m }_{ 2 }h }_{ 2 } } }$

(c)

$\frac { { m }_{ 1 } }{ { m }_{ 2 } } \sqrt { \frac { { h }_{ 1 } }{ { h }_{ 2 } } }$

(d)

$\frac { { m }_{ 1 } }{ { m }_{ 2 } }$

13. If an object is dropped from the top of a building and it reaches the ground at t = 4 s, then the height of the building is (ignoring air resistance) (g = 9.8 ms-2)

(a)

77.3 m

(b)

78.4 m

(c)

80.5 m

(d)

79.2 m

14. If a particle executes uniform circular motion in the xy plane in clock wise direction, then the angular velocity is in

(a)

+y direction

(b)

+z direction

(c)

-z direction

(d)

-x direction

15. Two objects are projected at angles 30° and 60° respectively with respect to the horizontal direction. The range of two objects are denoted as R30° and R60° Choose the correct relation from the following.

(a)

R30° =R6 ​​​​​​​

(b)

R30° =4R6

(c)

R30° =$\frac{R_{60°}}{2}$

(d)

R30° =2R6

16. What is the resultant vectors, when 2 vectors are at right angles to each other?

(a)

$R=\sqrt{P^2+Q^2}$

(b)

R=P+ Q

(c)

R=P-Q

(d)

$R=\sqrt \frac{P}{Q}$

17. A bus travelling the first one-third distance at a speed of 10 km/h, the next one-third at 20 km/h and at last one-third at 60 km/h. The average speed of the bus is

(a)

9km/h

(b)

16km/h

(c)

18km/h

(d)

48km/h

18. A car is moving along a straight road with a uniform acceleration. It passes through two points P and Q separated by a distance with. velocity 30 km/h and 40 km/h respectively. The velocity of the car midway between P and Q is

(a)

33.3km/h

(b)

20$\sqrt{2}$ km/h

(c)

25$\sqrt{2}$km/h

(d)

35km/h

19. In non-uniform circular motion, the resultant acceleration makes an angle with the radius vector is

(a)

$\tan^{-1}(\frac{ra_t}{V^2})$

(b)

$\tan_{-1}(\frac{a_t}{(\frac{r}{v^2})})$

(c)

$\tan^{-1}(\frac{rv^2}{at})$

(d)

$\tan^{-1}(\frac{r+at^2}{v^2})$

20. For a particle, revolving in a circle with speed, the acceleration of the particle is

(a)

along the tangent

(b)

(c)

along its circumference

(d)

zero

21. An object of mass m held against a vertical wall by applying horizontal force F as shown in the figure.The minimum value of the force F is

(a)

Less than mg

(b)

Equal to mg

(c)

Greater than mg

(d)

Cannot determine

22. 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

23. A machine gun has mass 15 kg. It fires 15 g bullet at the rate of 200 bullets per minutes with a speed of 150 m/s. Then the recoil velocity of the gun is,

(a)

20 ms-1

(b)

15 ms-1

(c)

150 ms-1

(d)

0.2 ms-1

24. A body whose momentum is constant must have constant

(a)

Force

(b)

Acceleration

(c)

Velocity

(d)

All

25. When a body is moving on a surface, the force of friction is called_____friction.

(a)

Static

(b)

Kinetic

(c)

Limiting

(d)

Rolling

26. First law of Newton deals with the:

(a)

concept of inertia alone

(b)

definition of force alone

(c)

either (a) or (b)

(d)

concept of inertia and definition of force

27. 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

28. If a car and a scooter have the same momentum, then which one is having greater speed?

(a)

scooter

(b)

car

(c)

both have same velocity

(d)

data insufficient

29. A bomb at rest explodes. The total momentum of all its fragments is

(a)

zero

(b)

infinity

(c)

always 1

(d)

always greater then 1

30. The angle of inclined plane with the horizontal such that an object placed on it begins to slide is

(a)

angle of friction

(b)

angle of repose

(c)

angle of response

(d)

angle of retardation

31. A ball of mass 1 kg and another of mass 2kg are dropped from a tall building whose height is 80 m. After, a fall of 40 m each towards Earth, their respective kinetic energies will be in the ratio of

(a)

$\sqrt2:1$

(b)

$1:\sqrt2$

(c)

2:1

(d)

1:2

32. A body of mass 1 kg is thrown upwards with a velocity 20 ms-1 It momentarily comes to rest after attaining a height of 18 m. How much energy is lost due to air friction?(Take g = 10 ms-2)

(a)

20 J

(b)

30 J

(c)

40 J

(d)

10 J

33. If the linear momentum of the object is increased by 0.1% then the kinetic energy is Increased by

(a)

0.1 %

(b)

0.2 %

(c)

0.4 %

(d)

0.01 %

34. A spring of force constant k is cut into two pieces such that one piece is double the length of the other. Then, the long piece will have a force constant of

(a)

$\frac{2}{3}$k

(b)

$\frac{3}{2}$k

(c)

3k

(d)

6k

35. An iron sphere of mass 8 kg has the same diameter as a copper sphere of mass 4 kg. Both spheres are dropped simultaneously from a tower. When they are 10 m above the ground, they have the same

(a)

acceleration

(b)

momenta

(c)

Potential Energy

(d)

Kinetic Energy

36. An engine pumps water continuously through a hose. Water leaves the hose with a velocity v and m is the mass per unit length of the water of the jet. What is the rate at which kinetic energy is imparted to water?

(a)

${{1}\over{2}}{m}{v}^{2}$

(b)

mv3

(c)

${{1}\over{2}}{m}{v}^{3}$

(d)

${{1}\over{2}}{m}{v}^{2}$

37. Which one of the following is not a conservative force?

(a)

Gravitational force

(b)

Electrostatic force between two changes

(c)

Magnetic force, between two magnetic dipoles

(d)

Frictional force

38. If a force F is applied on a body and the body moves with velocity v, the power will be

(a)

F.V

(b)

F/V

(c)

FV2

(d)

F/V2

39. For elastic collision, coefficient of restitution is

(a)

0

(b)

1

(c)

0 < e < 1

(d)

$\infty$

40. In a gravitational field, the work done in moving a body from one point into another depends on

(a)

initial and final positions

(b)

distance between them

(c)

actual distance covered

(d)

velocity of motion

41. A couple produces,

(a)

pure rotation

(b)

pure translation

(c)

rotation and translation

(d)

no motion

42. A rigid body rotates with an angular momentum L. If its kinetic energy is halved, the angular momentum becomes,

(a)

L

(b)

L/2

(c)

2L

(d)

L$\sqrt{2}$

43. A particle undergoes uniform circular motion. The angular momentum of the particle remain conserved about,

(a)

the center point of the circle.

(b)

the point on the circumference of the circle.

(c)

any point inside the circle.

(d)

any point outside the circle

44. A disc of the moment of inertia Ia is rotating in a horizontal plane about its symmetry axis with a constant angular speed $\omega$ Another disc initially at rest of moment of inertia Ib is dropped coaxially on to the rotating disc. Then, both the discs rotate with the same constant angular speed. The loss of kinetic energy due to friction in this process is,

(a)

$\frac { 1 }{ 2 } \frac { { I }_{ b }^{ 2 } }{ 2({ I }_{ a }+{ I }_{ b }) } { \omega }^{ 2 }$

(b)

$\frac { { I }_{ b }^{ 2 } }{ 2({ I }_{ a }+{ I }_{ b }) } { \omega }^{ 2 }$

(c)

$\frac { { ({ I }_{ b }-{ I }_{ a }) }^{ 2 } }{ ({ I }_{ a }+{ I }_{ b }) } { \omega }^{ 2 }$

(d)

$\frac { 1 }{ 2 } \frac { { { I }_{ b }{ I }_{ b } } }{ ({ I }_{ a }+{ I }_{ b }) } { \omega }^{ 2 }$

45. 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

46. A couple produces____ motion.

(a)

linear and rotational

(b)

purely rotational

(c)

purely linear

(d)

no

47. If I, $\alpha$ . and $\tau$ are MI, angular acceleration and torque respectively of a body rotating about any axis with angular velocity $\omega$ , then

(a)

$\tau =I\omega$

(b)

$\tau =I\alpha$

(c)

$\alpha =r\omega$

(d)

$\alpha =r\omega$

48. The dimension of torque is:

(a)

ML2T2

(b)

M2L2T2

(c)

ML2T-1

(d)

MLT-2

49. If r and k represent the radius and radius of gyration of a rolling body, the ratio of the rotational kinetic energy to the total kinetic energy of the body is

(a)

k2:r2

(b)

(k2 + r2) : r2

(c)

r2:(k2+r2)

(d)

k2:(k2+r2)

50. The moment of inertia of a body about a given axis is 1.2 kgm2. Initially, the body is at rest. In order to produce a rotational kinetic energy of 1500 joule, an angular acceleration 25 radian/sec2 must be applied about that axis lor a duration of

(a)

4 s

(b)

2 s

(c)

8 s

(d)

10 s

51. The linear momentum and position vector of the planet is perpendicular to each other at

(a)

perihelion and aphelion

(b)

at all points

(c)

only at perihelion

(d)

no point

52. A planet moving along an elliptical orbit is closest to the Sun at distance r1 and farthest away at a distance of r2. If v1 and v2 are linear speeds at these points respectively. Then the ratio ${v_1\over v_2}$ is

(a)

${r_2\over r_1}$

(b)

$({r_2\over r_1})^2$

(c)

${r_1\over r_2}$

(d)

$({r_1\over r_2})^2$

53. If the distance between the Earth and Sun were to be doubled from its present value, the number of days in a year would be

(a)

64.5

(b)

1032

(c)

182.5

(d)

730

54. The kinetic energies of a planet in an elliptical orbit about the Sun, at positions A, B and C are KA, KB and KC respectively. AC is the major axis and SB is perpendicular to AC at the position of the Sun S as shown in the figure. Then

(a)

KA > KB >KC

(b)

KB < KA < KC

(c)

KA < KB < KC

(d)

KB > KA > KC

55. An object of mass 10 kg is hanging on a spring scale which is attached to the roof of a lift. If the lift is in free fall, the reading in the spring scale is

(a)

98 N

(b)

zero

(c)

49 N

(d)

9.8 N