EXAMINATION PAPER: 2010

Time: 3 hours

Maximum Marks: 70

General Instructions:

1. All questions are compulsory.
2. There are 30 questions in total. Questions 1 to 8 carry one mark each, questions 9 to 18 carry two marks each, questions 19 to 27 carry three marks each and question 28 to 30 carry five marks each.

1. There is no overall choice. However, an internal choice has been provided in the one question of two marks; one question of three marks and all three questions of five marks each. You have to attempt only one of the choices in such questions.

1. Use of calculators in not permitted.
2. Please write down the serial number of question before attempting it.
3. You may use the following values of physical constant wherever necessary. Boltzmann's constant K = 1.38 x 10^-23 JK^-1 Avogadro's number <math>N_A = 6.022 \times 10^{23}</math>/mol Radius of Earth R = 6400 km.
4. Express one micron in metre.
5. What does the slope of velocity-time graph represent?
6. Are the magnitude and direction of <math>(\overline{A} - \overline{B})</math> same as that of <math>(\overline{B} - \overline{A})</math>? 1
7. What is the principle of working of a rocket?
8. Why do we slip on a rainy day?
9. What is the source of the kinetic energy of the falling rain drop?

Two bodies move in two concentric circular paths of radii r₁ and r₂ with same time period. What is the ratio of their angular velocities?

1. State second law of thermodynamics.
2. If <math>x = at + bt^2</math>, where x is in metre and t in hour, what will be the unit of 'a' and 'b'? 2
3. Physics

198

The displacement-time graph of two bodies P and Q are represented by OA and BC respectively. What is the ratio of velocities of P and Q?

<math>\angle OBC = 60^{\circ} \text{ and } \angle AOC = 30^{\circ}</math>

TOTAL ST 60

0 1/19/ ---- OR A car moving with a speed of 50 kmh^-1 can be stopped by brakes after at least 6 m. What will be the minimum stopping distance, if the same car is moving at speed of 100 kmh-1? 2

1. A particle of mass m is moving in an horizontal circle of radius 'r', under a centripetal force equal to (k/r2), where k is a constant. What is its potential energy? 2
2. Two solid spheres of the same are made of metals of different densities, which of them has larger moment of inertia about its diameter? Why? 2

If suddenly the gravitational force of attraction between the earth and a satellite revolving around it becomes zero, what will happen to the satellite? 2

1. When air is blown in between two balls suspended close to each other, they are attracted towards each other. Give reason. 2
2. What is an isothermal process?

Also give essential conditions for an isothermal process to take place.2

1. Calculate the fall in temperature of helium initially at 15°C, when it is

suddenly expanded to 8 times its volume. Given <math>\gamma = 5/3</math>. 2

Three vessels of equal capacity have gases at the same temperature and pressure. The first vessel contains neon (monoatomic), the second vessel contains chlorine(diatomic) and third contain polyatomic gas. Do the vessel contain equal number of molecules? Is the root-mean square speed of molecules same in three cases? 2

XI - Physics 199