FAISALABAD BOARD 2012
PAPER PHYSICS PART-I
Time: 20 Min.
(Objective Part
Marks: 17

Note: Four answer are given against each question in columns .4,B,C and D. Select the right answer and on the separate Answer Sheet, fill the circle A,B,C or D with pen or marker in front of that question number.

• The concept of entropy was introduced by Rudolph Clausius in:

(A) 1840   
(b) 1856  
(c) 1857       
(d) 1905

• Which one is tme for isothermal process:

(a) Q = W
(b) Q = 0
(c) W = 0
(d) W =

• The value of critical angle for glass-air boundary is:

(a) 41.8°
(b) 41.5°
(c) 42.8°
(d) 42°

• The wave nature of light was proposed by:

(a) Young
(b) Gallileo
(c) Huygen
(d) Newton

• Light from sun reaches the earth in forms of

(a) Spherical wave front 
(b) P1inte'wave front
(c) Elliprical wave front
(d) Hyperbolic wave front

• The time period of a wave s 0.2s. its frequemcy will be

(a) 2Hz 
(b) 3HZ
(c) 4HZ
(d) 5HZ

• The periodic increase and decrease in loudness of sound is called:

(a) Resonance      
(b) Interference
(c) Beats
(d) Polarization

• The wave form of S.H.M. is:

(a) Cosine wave     
(b) Sine wave
(c) Square wave
(d) Pulse wave

• Venturi meter is a device used to measure:

(a) Density of fluid    
(b) Speed of fluid
(c) Pressure of fluid  
(d)  Viscosity of fluid

• The minimum velocity necessary to put a satellite into orbit is:

(a) 7.1kms^-1         
(b) 7.3kms^-1
(c) 7.9kms^-1
(d) 8.9kins^-1

• Moment of inertia is equal to:

(a) mgr
(b) m²r²
(c) mr
(d) mr²

• The original source of tidal energy is:

(a) Moon
(b) Earth
(c) Sun
(d) Sea

• Motion of projectile is  dimension.

(a) One        
(b) Two
(c) Three       
(d) Four

• The magnitude of rectangular components are equal if its angle with x-axis is:

(a) 30°
(b) 45°
(c) 60°
(d) 90°

• The vector in space has components:

(a) One
(b) Two
(c) Three        
(d) Four

• The dimension ML°T° represent the quantity:

(a) Length
(b) Mass
(c) Time  
(d) Velocity

• 73.650 rounded of up to one decimal is:

(a) 73.6
(b) 73.7
(c) 74  
(d) 73.65

Time: 2:40 Hours
(Subjective Part)    
Marks: 68
SECTION-I:

2. Write short answer any Eight Parts.    16

• Write are the units of gravitational constant G in the formula F = G
• The period of a simple ( pendulum is measured by a stop watch. What types of errors are possible in the time period?
• Why do we find it useful to have two units for the amount of substance, the kilogram and the mole?
• Describe briefly, how we obtain the vector, when its rectangular components are given?
• Uner what conditions would a vector have components that are equal in magnitude'?
• Can a vector have a component greater than the vector's magnitude?
• Show that the rate of change of momentum is equal to force.
• Explain the circumstances in its path does a projectile have  its minimum speed, its maximum speed?
• Explain the circumstances in which the velocity v and acceleration d n a car are it) Parallel (ii) Anti-parallel
• Define kilowatt hour (kwh). Show 1kwh=3.6MJ
• When a rocket re-enters the atmosphere its nose cone becomes very hot. Where does this heat energy conic from?
• An object has 1J of potential energy. Explain what does it mean?

3. Write short answer any Eight Parts.    16

• Why does a diver change his body position before diving in the pool? '
• When mud flies the type of a moving bicycle, in which direction does it fly'? Explain.
• What are geostationary orbits and geostationary satellites'?
• Define terminal velocity.
• A person is standing near a fast moving car. Is there any danger that he will fall towards it?
• Explain what do you understand by the term viscosity?
• What is total distance travelled by an object moving with S.H.M. in a time equal to its period, if its amplitude is A?
• Can we realize an ideal simple pendulum?
• What are free and forced oscillations'?
• Why speed of sound is much higher in solids than in gases?
• Explain why sound travels faster in warm air than in cold air?
• What features do longitudinal waves have in common with transverse waves?

4. Write short answer any Six Parts.                          12

• Under what conditions two or more sources of light behave as coherent sources?
• Can visible light produced interference fringes? Explain.
• What is the difference between interference and diffraction?
• One can buy a cheap microscope for use by the children. The images seen in such a microscope have coloured images? Why is it so?
• What are different types of optical fiber?
• Find magnifying power of a convex lens of 25cm focal length act as a magnifying glass.
• State the Carrot's theorem.
• What is negative entropy? Give example and its unit.
• A thermo flask containing milk as system is shaken rapidly. Does the temperature of milk rise?

SECTION-II

5. (a) Explain what is meant by projectile motion. Derive expression for: (a) The time of flight (b) The range of projectile.   04
(b) The position of two aeroplanes at any instant are represented by into points A(2, 3, 4) and 13(5, 6, 7) from an origin in km. Calculate the distance between the two aeroplanes. 04

6. (a) What is moment of inertia'? Explain the moment of inertia of an irregular rigid body. 04
(b) How large a force is required to accelerate an electron (m= 9.1 x 10^-31kg) from rest to a speed of 2.0x 10⁷s m/s through a distance of 5.0cm.   04

7 (a) Show that Cp — Cv = R where Cp — Cv and R are molar specific heat at  constant pressure, molar specific heat at constant volume and universal gas constant respectively.    04
(b) Water flows through a hose, whose internal diameter is 1cm at a speed of 1m/s. What should be the diameter of the nozzle if the water is to emerge at 21m/s? 04

8. (a) What are defects in Newton's formula for speed of sound in air How this formula was corrected by Laplace'?            04
(b) A block of mass 4.0kg is dropped from a height of 0.80m onto z spring of spring constant K .1960Nm¹. Find the maximum distance through which the spring will be compressed. 04

9. (a) Explain Young's double slit experiment. Deriver formula for fringe spacing for dark and bright fringes.      04
(c) A converging lens of focal length 5.0cm is used as t magnifying glass. If the near point of the observer is 25cm ant the lens is held close to the eye. Calculate the angular magnifications. What is the angular magnification when the final image is formed at infinity? 04