FAISALABAD BOARD 2016
PAPER PHYSICS PART-I
Time: 20 Min.
(Objective Part)
Marks: 17
Note: You have four choice for each objective type question as A, B, C and D The choice which you think is correct; fill that circle in front of that question number. Use marker or pen to fill the circles. Cutting or filling two or more circles will result in zero mark in that question.

• The angular momentum L is given by:
  
  (a) -; x P
  (b) Ix;
  (c) r x F
  (d) F x-P

• The direction of angular velocity is determined by:
  
  (a) Left hand rule
  (b) Head to tail rule
  (c) Right hand rule
  (d) General rule

• The angle subtended by one complete circle at its center in radians is:
  
  (a) 360
  (b) 2ff
  (c)
  (d) yr

• Which is non conservative force?
  
  (a) Electric force
  (b) Magnetic force
  (c) Gravitational force
  (d) Frictional force

• A ball is thrown up with 20ms-1 at an angle of 60° with x-axis,the velocity of the ball at the top position is:
  
  (a) 0ms-1
  (b) 10ms-1
  (c) 20ms-1
  (d) 16ms-1

• Rate of change of momentum is equal to:
  
  (a) Force
  (b) Momentum
  (c) Impulse
  (d) Torque

• A force of 20N acts along x-axis, its x-component is:
  
  (a) ON
  (b) 10N
  (c) 20N
  (d) 30N
  
  
• The percentage uncertainty in radius of a sphere is 2%. The total percentage uncertainty in the volume of a sphere is:
  
  (a) 2%
  (b) 4%
  (c) 6%
  (d) 8%

• The measure of hotness or coldness of a substance is:
  
  (a) Temperature
  (b) Heat
  (c) Internal energy
  (d) Energy

• If the temperature of a system is kept constant, the process is called:
  
  (a) Isobaric
  (b) Isochoric
  (c) Isothermal
  (d) Adiabatic

• If an object is placed in between focus point and optical center of a convex lens, the image formed by lens is:
  
  (a) Real, inverted
  (b) Virtual, diminished
  (c) Virtual, inverted
  (d) Virtual, erected

• When a ray of light enters from denser into a rare medium, wavelength of light ray will:
  
  (a) Increase
  (b) Decrease
  (c) Unchanged
  (d) Cannot be determined
  
  
• Two waves having same frequency travelling along same line in opposite direction, will produce:
  
  (a) Interference
  (b) Stationary waves
  (c) Beats
  (d) Doppler's effect
  
  
• With the increase of temperature of air by 1°C, speed of sound increases by:
  
  (a) 0.61ms-1
  (b) 0.61cms'
  (c) 0.06ms-1
  (d) 0.06cms-1

• The speed of sound in air is 340 m/s. If the pressure of air is doubled then the speed becomes:
  
  (a) Double
  (b) Half
  (c) Four times
  (d) Remain same

• The ratio of the velocities of water in a pipe lying horizontally at two ends is 1 : 4. The ratio of diameters of pipe at these two ends is:
  
  (a) 1 : 2
  (b) 2 : 1
  (c) 1 : 4
  (d) 4 : 1
  
  
• The P.E. stored by a mass spring system at an extension of 2cm is 10J. The P.E. stored by the same system at an extension of 4cm will be:
  
  (a) 10J
  (b) 20J
  (c) 30J
  (d) 40J

Time:2.40 Hours
Subjective Part
Section I

2. Attempt any EIGHT short questions. (8 x 2 = 16)

• Define and explain supplementary units?
• Give drawbacks to use the period of a pendulum as a time standard.
• How many years in 1 second?
• What are derived units? Explain.
• Two vectors have unequal magnitudes. Can their sum be zero? Explain.
• Can a vector have a component greater than the vector's magnitude? Explain.
• Define unit vector and position vector.
• At what point or points in its path does a projectile have its maximum speed, its minimum speed?
• Explain the circumstances in which velocity -1,7 and acceleration a of a car are
  (i) antiparallel
  (ii) a = 0 but v # 0 .
• Define and derive the formula of range of projectile.
• State and explain Newton's second law of motion.
• Distinguish between elastic and inelastic collision.

3. Attempt any EIGHT short questions. (8 x 2 =16)

• What sort of energy is in (i) compressed spring (ii) a moving ear?
• A force F acts through a distance L. The force is then increased to 3F and then acts through a further distance of 2L. Draw the work diagram to scale.
• Define kWh and write its relation with Joule.
• A disc and a hoop start moving down from the top of an inclined plane at the same time. Which one will be moving faster on reaching the bottom? Explain.
• What is meant by moment of inertia? Explain its significance.
• Explain how many minimum number of geostationary satellites are required for global coverage of TV transmission?
• Name two characteristics of simple harmonic motion.
• What is the total distance travelled by an object moving with SHM in a time equal to its time period, if its amplitude is A?
• Define driven harmonic oscillator and damped oscillations.
• Explain the terms crest and trough.
• How are beats useful in tuning musical instruments?
• Describe two applications of Doppler effect.

4. Attempt any SIX short questions. (6 x 2 = 12)

• What are Newton's rings?
• How would you distinguish between unpolarized and plane polarized lights?
• How would you manage to get more orders of spectra using a diffraction grating?
• What is angular magnification?
• If a person was looking through a telescope at the full moon, how would the appearance of the moon be changed by covering half of the objective lens?
• Write any two postulates of kinetic theory of e„.3es.
• What are reversible and irreversible processes?
• Does entropy of a system increase or decrease due to friction?
• Can the mechanical energy be converted completely into heat energy? If so, give an example.

Section II

Question#5
(a) Define vector product of two vectors and also describe its characteristics.
(b) Find the angle of projection of a projectile for which maximum height and horizontal range are equal.

Question#6
(a) What is meant by rotational kinetic energy? Using this to find velocity of disc and hoop at the bottom of an inclined plane.
(b) Ten bricks, each 6.0cm thick and mass 1.5kg, lie flat on a table. How much work is required to stack them one on the top of another?

Question#7

(a) State and derive the equation of continuity for an ideal fluid.
(b) 336J of energy is required to melt lg of ice at 0°C. What is the change in entropy of 30g of water at 0°C as it is changed to ice at 0°C by a refrigerator?

Question#8
(a) What is effect of temperature on speed of sound? Also derive a formula to find the rise of speed with temperature.
(b) A spring, whose spring constant is 80N till , vertically supports a mass of lkg in the rest position. Find the distance by which the mass must be pulled down, so that on being released, it may pass the mean position with a velocity of

Question#9
(a) Describe the construction and working of Michelson's interferometer.
(b) An astronomical telescope having power of 5 consists of two thin lenses 24cm apart. Find the focal lengths of the lenses.