text: • question_answer A particle is projected form the ground with an initial velocity of 20 m/s at an angle of $30{}^\circ$with horizontal. The magnitude of change in velocity in a time interval from t = 0 to t = 0.5 s is $(g=10m/{{s}^{2}})$ A) 5 m/s B) 2.5 m/s C) 2 m/s                D) 4 m/s
  
  [A] During motion force acting on particle only in downward direction i.e. mg so only its vertical velocity change during the motion $a=\frac{mg}{m}=g\,\,downward$ ${{v}_{y}}={{u}_{y}}+gt$ ${{v}_{y}}-{{u}_{y}}=gt$ $\Delta v=gt=10\times 0.5=5m/\sec$