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#### +1 Second Revision Test Question Answer

11th Standard

Reg.No. :
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Physics

Time : 02:30:00 Hrs
Total Marks : 70
15 x 1 = 15
1. A length-scale (I) depends on the permittivity (e) of a dielectric material,  Boltzmann constant (kB), the absolute temperature (T),  the number per unit volume (n) of certain charged particles, and the charge (q) carried by each of the particles. Which of the following expression for I is dimensionally correct?

(a)

$l=\sqrt{{{nq^2}\over{\epsilon {k}_{B}T}}}$

(b)

$l=\sqrt{{{\epsilon {k}_{B}T}\over{nq^2}}}$

(c)

$l=\sqrt{{{q^2}\over{e{n}^{{{2}\over{3}}}{k}_{B}}T}}$

(d)

$l=\sqrt{{{q^2}\over{\epsilon n{k}_{B}T}}}$

2. If a particle executes uniform circular motion, choose the correct statement

(a)

The velocity and speed are constant

(b)

The acceleration and speed are constant.

(c)

The velocity and acceleration are constant.

(d)

The speed and magnitude of acceleration are constant.

3. If $|\vec P\times \vec Q|=|\vec P.\vec Q|$, then angle between $\vec P$ and $\vec Q$ will be

(a)

0o

(b)

45o

(c)

90o

(d)

180o

4. A book is at rest on the table which exerts a normal force on the book. If this force is considered as reaction force, what is the action force according to Newton's third law?

(a)

Gravitational force exerted by Earth on the book

(b)

Gravitational force exerted by the book on Earth

(c)

Normal force exerted by the book on the table

(d)

None of the above

5. A particle which is constrained to move along x-axis, is subjected to a force in the same direction which varies with the distance x of the particle from the origin as F(x) =kx + ax3. Here, k and a are positive constants. For x≥0, the functional form of the potential, energy U(x) of the particles

(a)

(b)

(c)

(d)

6. A particle is moving with a constant velocity along a line parallel to positive X-axis. The magnitude of its angular momentum with respect to the origin is,

(a)

zero

(b)

increasing with x

(c)

decreasing with x

(d)

remaining constant

7. A circular disc is rolling down in an inclined plane without slipping. The percentage of rotational energy in its total energy is

(a)

66.61%

(b)

33.33%

(c)

22.22%

(d)

50%

8. The work done by the Sun’s gravitational force on the Earth is

(a)

always zero

(b)

always positive

(c)

can be positive or negative

(d)

always negative

9. If the temperature of the wire is increased, then the Young’s modulus will

(a)

remain the same

(b)

decrease

(c)

increase rapidly

(d)

increase by very a small amount

10. If there were no gravity, which oftbe following will not be there for a fluid?

(a)

viscosity

(b)

surface tension

(c)

pressure

(d)

archimedes upward thrust

11. When a uniform rod is heated, which of the following quantity of the rod will increase

(a)

mass

(b)

weight

(c)

center of mass

(d)

moment of inertia

12. The ratio $\gamma =\frac { { C }_{ p } }{ { C }_{ V } }$ for a gas mixture consisting of 8 g of helium and 16 g of oxygen is

(a)

23/15

(b)

15/23

(c)

27/11

(d)

17/27

13. The damping force on an oscillator is directly proportional to the velocity. The units of the constant of proportionality are

(a)

kg m s−1

(b)

kg m s−2

(c)

kg s−1

(d)

kg s

14. Two simple pendulums of time periods 2.0 s & 2.1 s are made to vibrate simultaneously. They are in phase initially, after how may vibrations are there in the same phase?

(a)

21

(b)

25

(c)

30

(d)

35

15. A transverse wave moves from a medium A to a medium B. In medium A, the velocity of the transverse wave is 500 ms-1 and the wavelength is 5 m. The frequency and the wavelength of the wave in medium B when its velocity is 600 ms-1, respectively are

(a)

120 Hz and 5 m

(b)

100 Hz and 5 m

(c)

120 Hz and 6 m

(d)

100 Hz and 6 m

16. 6x 2 = 12
17. Deduce dimensional formulae of Boltzmann's constant

18. An object is thrown vertically downward. What is the acceleration experienced by the object?

19. Can a single isolated force exist in nature? Explain your answer

20. Define the different types of potential energy?

21. When a tree is cut, the cut is made on the side facing the direction in which the tree is required to fall. Why?

22. Define stress and strain.

23. State the second law of thermodynamics in terms of entropy.

24. Write down the equation of time period for linear harmonic oscillator.

25. What is Reverberation?

26. 6 x 3 = 18
27. In a physical units, how many units are there in 1 metre?
1 micron ($\mu$) = 10-6 m
Given data:
1 AU = 1.496 x 1011m
1 ly = 9.467 x 1015m
1 mm = 10-6m
1 parsec = 3.08 x 1016m

28. The following graphs represent position-time graphs. Arrange the graphs in ascending order of increasing speed.

29. Define one newton

30. What is the stopping distance for a vehicle, of mass m moving with speed v along a level road, if the co-efficient of friction between the tyres and the road is $\mu$?

31. A metre stick is balanced on a knife edge at its centre. When two coins, each of mass 5 g are put one on top of the other at the 12.0 cm mark, the stick is found to be balanced at 45.0 cm, what is the mass of the meter stick?

32. A particle is projected upward from the surface of the earth (radius) with a K.E equal to half the minimum value needed for it to escape. To which height, does it rise above the surface of earth?

33. Write the main features of the prevost theory

34. State and explain Boyle's law.

35. Calculate the speed of sound in a steel rod whose Young’s modulus Y = 2 × 1011 N m-2 and $\rho$ = 7800 kg m-3.

36. 5x 5 = 25
1. Obtain an expression for the time period T of a simple pendulum. The time period T depend upon (i) mass 'm' of the bob (ii) length 'l' of the pendulum and (iii) acceleration due to gravity g at the place where the pendulum is suspended. (Constant k = 2π) i.e

2. Define and illustrate the following terms. (i) Equal vectors, (il) Parallel vectors, (iii) Anti-parallel vectors, (iv) Unit vector.

1. Identify the free body diagram that represents the particle accelerating in positive x direction in the following.

2. Find the work done in pulling and pushing another though 200 m horizontally when a force of 1000N is acting along a chain making an angle of 60° with ground. Assume the floor to be smooth friction less surface.

1. Derive an expression for the Center of Mass of Two Point Masses.

2. Derive an expression for energy of satellite.

1. State and prove Bernoulli’s theorem for a flow of incompressible, non-viscous, and streamlined flow of fluid.

2. Estimate the mass of air in your class room at NTP. Here NTP implies normal temperature (room temperature) and 1 atmospheric pressure

1. State Newton's law of cooling verify with an experiment.

2. Calculate the equivalent spring constant for the following systems and also compute if all the spring constants are equal: