question_answer 45)

  A boy is moving on a straight road against a frictional force of 5 N. After travelling a distance of 1.5 km, he forgot the correct path at a roundabout of radius 100 m as shown in figure. However, he moves on the circular path for one and half cycle and then he moves forward up to 2.0 km. calculate the work done by him.                

Answer:

  Given, force applied by boy against friction=5N Displacement on the circular path = One cycle + Half cycled = 0 + Half cycle = 0 + Diameter of circular path   (Displacement depends on initial and final point) = 0 + 2 r = 0 + 2 x 100                 [r = 100 m] = 0 + 200 = 200 m Total displacements = 1.5 km+200m+ 2.0km = 1.5 x 1000 + 200+2x 1000km                                 (1 km= 1000m) = 3700 m Work done by boy