Page 1 - HA
P. 1

SAI INTERNATIONAL SCHOOL
                                    CLASS-IX   PHYSICS HOME ASSIGNMENT-15
                   OBJECTIVE


                   MCQ(BOARD)

               1. A stone released with zero velocity from top of the tower reaches the ground in 4 sec.
               The height of the tower is about

               (a) 20 m       (b) 80 m

               (c) 40 m       (d) 160 m

               2. If a ball is thrown vertically upwards with 40 m/s, its velocity after two sec will be

               (a) 10 m/s     (b)    30 m/s

               (c) 20 m/s     (d)    40 m/s



               NUMERICALS:
                   1.  A stone is dropped from the top of a building of height 45 m. Calculate its

                                                                             2
                       velocity, when it strikesthe ground. (Take g=10 m/s ).
                   2.  A body is thrown up with a velocity of 29.4m/sec.Find the time taken by the body

                       to reach its highest point? After how much time the body will come back on the

                       ground?
                   3.   To estimate the height of a bridge over a river, a stone is dropped freely in the

                       river from the bridge. The stone takes 2 seconds to touch the water surface in the
                                                                                                   2
                       river. Calculate the height of the bridge from the water level. (g = 9.8 m/s ).
                   4.  If the planet existed whose mass and radius both were half those of the earth,

                       then what will be the acceleration due to gravity at its surface?
                   5.  How can you calculate the value of acceleration due to gravity?

                   6.  A ball is thrown vertically upwards with a velocity of 49 m/s. Calculate
                       (a) The maximum height to which it reaches

                       (b) The total time it takes to return to the surface of the earth.




                                                              1
   1   2   3