A block of mass 10 kg , moving in x direction with a constant speed of 10 m s - 1 , is subjected to a…

A block of mass 10 kg, moving in x direction with a constant speed of 10 s-1 , is subjected to a retarding force F=(0.1)xJ m-1 during its travel from x=20 m to 30 m . Its final kinetic energy will be:
  1. 475 J
  2. 450 J
  3. 275 J
  4. 250 J

Solution

m=10 kg, u=10 m s-1
Final KE will be given by
KEf=KEi+W
=12mu2+2030-0.1xdx
=12×10×100+-0.1x222030 
=500+-0.12900-400
KEf=500+-0.15002=475 J

Asked in: NEET 2015 (Phase 1)

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