A block of mass 1 kg is positioned at point A on a rough track, as shown in the figure. When given a slight push to the right, it comes to rest at point B on the track. Determine the work done by the frictional force on the block during its journey from A to B .

Step-by-step solution

Using the work-energy theorem: W_ net = K W_ gravity + W_ friction = K_B - K_A Since the block starts from rest (given a slight push) and comes to rest at B , K_A = 0 and K_B = 0 . The work done by gravity is: W_ gravity = mg(h_A - h_B) Substituting m = 1 kg , g = 10 m/s ^2 , h_A = 1.0 m , and h_B = 0.8 m : W_ gravity = 1 10 (1.0 - 0.8) = 2 J Therefore, the work-energy equation becomes: 2 + W_ friction = 0 W_ friction = -2 J