RAWALPINDI BOARD 2013
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.

• 1.275 has significant digits:

(a) 2
(b) 3
(c) 4
(d) 5

• A force of 10N makes an angle of 30° with Y-axis. The magnitude of x-component will be:

(a) 5N
(b) 8.66N
(c) 10N
(d) Zero

• If a force of 10N acts on a body of mass 5 kg for one second, then its rate of change of momentum will be:

(a) 10K.g.msec^-2
(b) 50 K.g.m sec^-2
(c) 5 K.g.msec^-2
(d) 2 K.g.msec^-2

• Rate of change of momentum is equal is:

(a) Force
(b) Impuse
(c) Torque
(d) Inertia

• Which one is conservative force?

(a) Electric force
(b) Tension in string
(c) Propulsion force of motor
(d) Normal force

• Orbital speed of satellite can be determined by:
  (a) v
  (b) v =  
  (c) v =
  (d) v =   
  

• Rotational K.E. for a disc is given as:

(a) mv2
(b) mv2
(c)
(d)  

• The largest satellite system is managed by the countries:

(a) 126
(b) 136
(c) 120
(d) 3

• The term I/ 2 /v2 in Bernoulli's equation has same units as:

(a) Work
(b) Volume
(c) Pressure
(d) Force

• Mass attached to spring is pulled slowly from mean position to X_o Then work done will be:

(a) kx_o
(b) kx_o²
(c) kx_o
(d) w²x_o

• Which one is correct relation for one end closed pipe.

(a) λn= 2I/n
(b) λn= 4I/n
(c) λn= nvI /I
(d) λn= nvI /4 I

• Speed of sound at t°C is given as:

(a) vt =v_o+0.6It
(b) vt =v_o+0.6It
(c) vt =v_o+0.6It
(d) vt =v_o+0.6It

• Distance between crest and trough is:

(a) λ
(b) λ / 2
(c) λ/ 4
(d) 2λ

• The phase difference between two points on wave front is:

(a) Zero
(b) π/4
(c) π/2
(d) π

• Final image of compound microscope is:

(a) Virtual and errect
(b) Virtual and inverted
(c) Real and inverted
(d) Real and errect

• Pressure of a gas is given by the relation:

(a)  <v²>
(b)  <v²>
(c)  <v²>
(d) /<v²>

• JK ^-1 is the unit of :

(a) Efficiency
(b) Entropy
(c) Internal energy
(d) Heat of fusion

Time: 3:10 Hours
(Subjective Part)
Marks:83

Section II

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

• Give the drawbacks to use the period of a pendulum as a time standard.
  
• The period of a simple pendulum is measured by a stop watch. What type of errors ale possible in the time period?
  
• Can a body rotate about its centre of gravity under the action of its weight?
  
• Two vectors have unequal magnitudes. Can their suns be zero? Explain.
  
• Find the velocity of light body after elastic collision with the stationary heavy body.
  
• At what point or points in its path does a projectile have its minimum speed and maximum speed.
  
• Explain the circumstances in which the velocity 'V' and acceleration 'a' of a car are
• Parallel
• Anti-Parallel.
• Two row boats moving parallel in the same direction are pulled towards each other, Explain.
  
• Write down dimension of
  
  • (a) Pressure
    
  • (b) Density.
    
• How many seconds are in one year?
  Prove that = *.
  Find the height of the projectile.

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

• What sort of energy is in
  
  • (a) compressed spring
    
  • (b) Water in a high dam?
    
• A girl drops a cup from a certain height which breaks into pieces. What energy changes are involved?
• Why does a diver change its body position before and after diving in the pool?
• What is the total distance travelled by an object moving with S.H.M in a time equal to its period, if its amplitude is A?
• Under what conditions does the addition of two S.H.Motions produce a resultant which is also Simple Harmonic?
• What is meant by phase angle? Does it define angle between max displacement and deriving force?
• What are geostationary satellites?
• What is meant by moment of inertia? Explain its physical significance.
• Write down work energy principle.
• Why sound waves travel faster in solids than in gases?
•  Define two kinds of progressive waves.
• How are beats useful in tuning musical instruments?

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

• In Young's experiment, one of the slits is covered with blue filter and other with red filter. What would be the pattern of light intensity on the screen'?
• How would you manage to get more orders of spectra using a diffraction grating?
• One can buy a cheap microscope for use by the children. THe images seen in such a microscope have coloured edges. Why is this so?
• Why does the pressure of a gas in a car tyre increase, when it is driven through distance?
• A thermos tlask containing milk as a system is shaken rapidly. Does the temperature of milk rise?
• Explain interference in thin films.
• Define Charles law.
• Define heat engine.
• How the power is lost in optical fiber through dispersion? Explain.

 Attempt any THREE questions. (8 x 3 = 24)

5. (a) Define and explain scalar product and also write down its four characteristics.
(b) A helicopter is ascending vertically at the rate of 19.6ms-I . When it is at the height of 156.8m above the ground, a stone is dropped. How long does this stone take to reach the ground?

6. (a) Define and explain Artificial gravity.
(b) A 70 kg man runs up a long flight of stairs in 4.0s. The verticaly height of the stairs is 4.5m. Calculate his power output in watts.

7. (a) What is Doppler's effect? Calculate the apparent frequency when the observer moves towards or away from the stationary source.
(b) A block of mass 4.0 kg is dropped from a height of 0.80m on a spring constant K = 1960Nm-1. Find the maximum distance through which the spring will be compressed.

8. (a) Explain the principle, construction and magnifying power of a compound microscope with the help of a ray diagram.
(b) A light is incident normally on a grating which has 2500 lines per centimeter. Compute the wave length of a spectral line for which the daviation in second order is 15.0°.

9. (a) State and prove Bernaulli's equation.
(b) A heat engine performs 100J of work and at the same time rejects 400J of heat energy to the cold reservoirs. What is the efficiency of the engine?

Attempt any THREE questions. (5x3 = 15)

10. (a)

• Derive the formula g =  to be used in free fall.
  
• What is meant by pithc of screw guage? Also give its least count.
  
• If the bob of the pendulum is replaced by another bob of different material, what will be the effect on time period?
  
• The resonating length of the sonometer wire is 10cm with a tuning fork of frequency 480 hertz. What should be its length with a tuning fork of frequency 320 hertz.
  
• What is end correction?
  
• Find the critical angle of glass, if its refractive index is 1.52.
  
• What are the sources of error during the experimental determination of focal length of a convex lens by displacement method?
  
• Design a table of observations to prove law of simple pendulum, i.e., time period is independent of the amplitude.

(b) Write down the brief procedure to determine experimentally the value of 'g' by free fall using electronic timer/ticker timer OR Write down the brief procedure to determine experimentally the focal length of convex lens by displacement method.

(c) Answer the following questions on the basis of graphs drawn below. For Graph A:
picture

• What can you conclude from the graph?
• Measure the length of second's pendulum from the graph?

OR
picture

• Find the slope of graph.
• Find the focal length of lens.