A block of mass 10 ~kg is moving in x -direction with a constant speed of 10 ~m / s . It is subjected to a retarding force F=0.1 x joule/metre during its travel from x=20 ~m to x=30 ~m . Its final K.E. will be

Step-by-step solution

Initial K.E., E₁= 1 2 m v^2 = 1 2 10 (10)^2=500 ~J At x=20 ~m , retarding force, F₁=0.1 20=2 ~N At x=30 ~m , retarding force, F₂=0.1 30=3 ~N . Average Retarding Force F= F₁+F₂ 2 = 2+3 2 =2.5 Work done by retarding force = loss in K.E. =F s=2.5(30-20)=25 ~J Final K.E. =E₁- loss in K.E. =500-25=475 ~J