text: Work Energy Theorem
  Question
  
  # A sphere of mass 2 kg is moving on a frictionless horizontal table with velocity v. It strike with a spring of constant 1 N/m and compresses it by 4 m. The velocity (v) of the sphere is :
  
  Moderate
  Solution
  
  ## As per work energy theorem  ${\mathrm{w}}_{\mathrm{sp}}=\mathrm{\Delta K}.\mathrm{E}$$⇒\frac{1}{2}{\mathrm{Kx}}^{2}=\frac{1}{2}{\mathrm{mv}}^{2}$$⇒\mathrm{v}=\sqrt{\frac{\mathrm{K}}{\mathrm{m}}}\mathrm{x}$$=\sqrt{\frac{1}{2}}.4=2\sqrt{2}\text{\hspace{0.17em}}\mathrm{m}/\mathrm{s}$
  
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