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84                                                                                     PHYSICS

                                                  v (   sinq o ) 2
                                             h  m  =  o
                                                     2g
                                   The time taken to reach this height is :

                                               o
                                          t m  =  v sin θ o
                                                g
                                   The horizontal distance travelled by a projectile from its initial position to the position
                                   it passes y = 0 during its fall is called the range, R of the projectile.  It is :
                                             v  2
                                          R =  o  sin2θ
                                              g      o
                              17.  When an object follows a circular path at constant speed, the motion of the object is
                                   called uniform circular motion. The magnitude of its acceleration is   a  = v /R. The
                                                                                                      2
                                                                                                  c
                                   direction of a  is always towards the centre of the circle.
                                               c
                                   The angular speed ω, is the rate of change of angular distance. It is related to velocity
                                                                      2
                                   v by   v = ω R.  The acceleration is a  = ω R.
                                                                  c
                                   If T  is the time period of revolution of the object in circular motion and ν  is its
                                                                           2 2
                                   frequency, we have ω = 2π ν, v = 2πνR,  a  = 4π ν R
                                                                      c
























































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