Class X important question of science

Class 10                                                                            F.M   20

                                                                                                                                                                                               P.M.    8

GROUP 'A': PHYSICS + CHEMISTRY

1.      (a)  State Newton's Universal law of Gravitation. Established the relation between Gravitational force of attraction, if masses are make double and they are separated by constant distance's'. If  distance between Mars and Earth is m and their attraction force is  [ Mass of earth and Mars is Kg and  respectively]     (1+2.5+2.5=6)

(b)  Write down the difference between g and G. Established the relation of g at the depth of earth. Also find the value of g at 5400km height from the earth center and g at center.                          (2+1.5+1+0.5=5)

 2.     (a)  Why an object at elevator feels its weight zero if elevator is falling freely? Why mass of any substance is constant all over the universe? What are the condition required for free fall on the Earth?                    (2+1+1=4)

      (b)  Where has more weight of an object of mass 10Kg if it is placed at earth and moon? Calculate. It is not necessary to provide external energy for revolving satellite around the earth why? Find the weight of an object of mass 50Kg, if it is placed at 9400Km from the earth center. Weight of that object at surface of earth is 500Kg m/s² Radius of earth is  

cm                                            (1.5+1.5+2=5)