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Thursday, 1 December 2016

physics grade 8

SECTION: A                                         Marks :  (12)
Q#1. Choose the correct answer .
        i.            The unit of acceleration is_____________
a)      ms                   b)  ms²                     c) m²s²                          d) ms
      ii.            The Pin hole camera is invented by__________
a)      Al-Kindi                        b) Al-Beruni          c) Ibn-ul-Haithem         d) Newton
    iii.            A spring  balance is used to measure the __________ of a body.
a)        Momentum       b) Weight            c) Mass                        d) Motion
     iv.            If  Fx and Fy are rectangular components, then F = ____________
a )                                                  b)
c.)                                                    d)
      v.            For  a body is thrown vertically upward, the value of “g” is________
a)      Positive           b) Negative              c) Equal                    d) Constant
    vi.            The rate of change of velocity of a body is known as__________
a)      Displacement  b) Speed                  c) Accelaration     d) None of these
  vii.            The  motion of Fan is  the example of _______ motion.
a)      Translatory    b)  Vibratory        c) Rotatory                         d) Random
viii.            The error , which  effect  equally  all measurement taken with the same instrument  is called
a)      Random  Error    b) Systematic  Error      c) Personal Error      d) None Of these
    ix.            The  meter rod can measure the length of a body correct up to________
a)      1 mm               b)  0.1 mm                 c) 0.01mm               d) 10 mm
      x.            Action and reaction are equal in magnitude but ___________ in direction.
a)      Same               b) Opposite              c)  Parallel                d) same
    xi.            A body is more stable if its center of gravity is________
A) Low             B) High                       C) May be anywhere   D) None
  xii.             The decomposition of vector into its rectangular component is called _____of vector?
A)     Addition                       B) Subtraction             C) Resolution               D)None







        SECTION : B                 (33)      
NOTE:-  Attempt any 11 parts   (11x3)
                         I.            Define motion? Also explain types of motion          
                      II.            The height of a racing car is kept small. Why?
                   III.            Define Torque? Also write its mathematical expression? On which factors torque depends?
                    IV.            Why First Law called Law of motion is called Law of inertia?
                       V.            How do we know whether a body is in a stable or unstable state of equilibrium due to position of its center of gravity?
                    VI.            Define friction? Also write Advantages and Disadvatages of Friction?
                 VII.            Differentiate between mass and weight?
              VIII.            A submarine dives 50 m at an angle of 30 wirh the horizental surface of the sea. How deep the  submarine is from the surface?
                    IX.            State Newton  2nd Law of motion?
                       X.            Give an example of a case when the resultant force is zero but resultant of torque is not zero?
                    XI.            A) It is difficult to walk on muddy ground. Explain Why?
B)We fall forward when car suddenly stop. Explain Why?
                 XII.            A rocket is moving vertically upward 5 kg fuel gas is released out of it in the downward with a velocity of 5000 ms. If the ,mass of rocket is 1000 kg. What will be its velocity?
              XIII.             Define AstroPhysics, Electromegnatism, And Machanics?
               XIV.            A) Under what condition the distance and displacement between two points will equal?  
B) Which are those two vectors whose resultant vector is zero?
                  XV.            What is head to tail rule?          
        SECTION : C                 (20)
NOTE:-  Attempt any two questions  (10 x 2)
Q#1)  A)  Prove that    2aS = Vf ² - Vi²                                                                                      (4)
B)  The mass of an astronaut is 100 kg.          i) What will be his weight on earth?   II)  Find its weight on moon. The value os gravitational acceleration on moon is 1.6 ms ?               (3)
C) Define Errors?  Also explain its types?                            (3)
Q#2)  A) State and explain Law of conservation of momentum with examples?       (4)
  B)   Define Equilibrium? Also Explain States of Equilibrium?                      (4)
  C) A body moves along a straight line from rest with an acceleration of 2 ms . Calculate the time taken by it to cover the distance of 100 m?                                                (2)
Q#3)  A) Define Resolution of vector? Resolve vector F into its Rectangular Component? Also find magnitude and direction of resultant vector?                           (6)
         B)  Explain Ist condition of Equilibrium with example?                                                             (4)

 THE END
     




































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