Try out this sample question and answer it in your H.W. book.
Date of submission: 031115
KENDRIYA VIDYALAYA, PATTOM
HALF YEARLY SAMPLE QUESTION
CLASS XI PHYSICS Max. marks:70
General Instructions:
i. All questions are compulsory.
ii. There are 23 questions. Qns.15 carry 1 mark each, Qns.610 carry 2 marks each, Qns.1122 carry 3 marks each, Qns.2426 carry 5 marks each.
iii. Qns.23 is a value based question and carry 4 marks.
iv. Overall choice is not allowed. However, internal choices are provided. You are to attempt only one of the choices in such questions.
v. You may use the following physical quantities wherever required.
c= 3 x 10^{8}m/s.
Planck’s constant, h= 6.626 x 10^{34} Js.
Boltzmann constant k= 1.381 x 10^{23} J/K.
Avogadro’s number N_{A} = 6.022 x 10 ^{23} mole^{1}.
Radius of earth= 6400 Km.
Mass of earth = 6 x 10^{24 }Kg.
1) What is the numerical ratio of velocity to speed of an object?
2) Can a body have constant speed and still have a varying velocity? Explain:
3) Why a pilot looping a vertical loop not fall down even at the highest point?
4) Why is it more difficult to revolve a stone tied to a larger string than a stone tied to a smaller string?
5) The velocity of a moving particle is given by V = 6 + 18t + 9t^{2} where x is in meters and t is in seconds. What is its acceleration at t=2 s?
6)





The escape velocity V of a body depends upon ( i ) the acceleration due to gravity of the planet (g) (ii) the radius of the planet (R). Dimensionally establish a relationship between V, g and R.
7) The graph gives the position time (xt) graphs

for two children A and B returning from school


O to their homes P and Q respectively. Now,


answer the following questions.
(a) Who lives closer, A or B?
(b) Who started earlier from school, A or B?
(c) Who walked faster, A or B?
(d) Who reached home earlier, A or B?
8) State and prove Polygon law of vector addition:
9) Define angle of friction. Show how it is related with coefficient of static
friction: OR
Define angle of repose. Show how it is related with angle of friction?
10) A light body and a heavy body have the same kinetic energy. Which one
will have the greater momentum? Give reason for your answer:
11) The shadow of a tower standing on a level plane is found to be 50m
longer when sun’s altitude is 30^{0} than when it is at 60^{0}. Find the height of the tower.
h
12) Derive graphically the following equations of motion for a uniformly
accelerated motion:
(a) s= ut + ½ at^{2}
(b) v^{2}u^{2} = 2as
13) Define relative velocity . Deduce an expression for relative velocity of an
object with respect to another in terms of their velocities relative to
earth. Hence, draw positiontime graphs of two objects moving along a
straight line, when their relative velocity is:
(i) +ve, (ii) ve (iii) zero
14) If = 3 + 2 and If = – 2 +3 , find the magnitude of ( + ) and
OR
Find the angle between the vectors = + 2 – and = + 2 .
15) Consider a body of mass m tied to one end of a string and rotating in a
vertical circle of radius r. Show that the minimum velocity of projection
at the lowest point for looping the loop is v = .
16) Prove the work energy theorem for a variable force.
17) What will be the duration of a day, if earth suddenly shrinks to of
its original volume, mass remaining the same?[M.I of solid sphere = MR^{2}^{ }]
18) Derive an expression for moment of inertia of a ring about a tangent in
its own plane. Given, moment of inertia of a ring about an axis through
its centre and perpendicular to its plane = MR^{2}/2.
19) State the principle of conservation of angular momentum. Give any two
practical applications.
20) Define escape velocity. Derive an expression for escape velocity of a
body from the surface of earth.
21) Moon has no atmosphere. Why?
22) What are conservative and non conservative forces? Give examples.
23) One rainy day, Devu was returning back home from school with her
elder sister Malu. On the way back home, they saw a running boy skidding and falling. Both the girls helped the boy to get up. Then, Devu asked her sister why after a rain we skid and fall.
(a) What might be the reason Malu has given to Devu?
(b) Give two values exhibited by the girls.
24) Define projectile. Show that its path is parabolic. Also, find expressions
for (i) maximum height attained and (ii) time of flight.
OR
Define centripetal force. Derive an expression for the centripetal
acceleration of a body moving with uniform speed v along a circular path
of radius r. show that it acts along the radius towards the centre of the
circular path.
25) State the law of conservation of mechanical energy. Show that the total
mechanical energy of a body falling freely under gravity is conserved.
Show it graphically.
OR
Define elastic collision. Prove that the relative velocity of approach
before collision is equal to relative velocity of separation after collision.
Hence, derive expressions for velocities of two bodies after collision
in terms of their initial velocities before collision.
26) Obtain an expression for acceleration due to gravity on the surface of
earth. Discuss its variation with altitude, depth and shape of earth.
OR
Define orbital velocity and time period of a satellite. Derive expressions
for these.
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