Question

h d2 d1 A girl pulls a box of mass m = For the first d1 = 6 m, there is no friction between the box and the floor. For the next d2 4 m the coefficient of friction between the box and the floor is u 0.2. 3 kg across a floor with a constant horizontal force F 25 N. Initially the block is at rest. 1) What is the work done on the box by the girl in moving the box over the distance di1 d2? Submit Help 2) What is work done on the box by friction in moving the box over the distance di +d2? Woor Submit Help 3) What is the final speed of the (after being pushed to di +d2)? Ve m/s Submit Help

Answer 1

Work done is given by net force x displacement by the net force. In the case of distance d1 , the net force acting on the body is F=25. In case of d2 , the net force is given by the Force applied F - friction force and the word done will be because of this net force.

force x displacement Work done dz Net farce in distance frictien A- frichion Net force 25 Total work done Net force x d2 25 x 6 +19x 4 226丁

Fiction force N Work done -1 24J lock til Tstal work done di td2 226 JyF. Cens enuing norgy 2 X mxV dx Q26 12-3 m/s