A 3.57 kg block is drawn at constant speed 4.06m along ahorizontal floor by a rope. The force on the block from therope has a magnitude of 7.68 N and is directed 15.0 degrees abovethe horizontal. What are (a) the work done by the rope'sforce, (b) the increase in thermal energy of the block-floorsystem, and (c) the coefficient of kinetic friction between theblock and floor? A 3.57 kg block is drawn at constant speed 4.06m along ahorizontal floor by a rope. The force on the block from therope has a magnitude of 7.68 N and is directed 15.0 degrees abovethe horizontal. What are (a) the work done by the rope'sforce, (b) the increase in thermal energy of the block-floorsystem, and (c) the coefficient of kinetic friction between theblock and floor?
Explanation / Answer
Mass m = 3.57 kg Length L = 4.06 m Force F = 7.68 N angle = 15 degrees (a). work done by the rope's force = F cos *L = 30.118 J (b). the increase in thermal energy of the block-floor system= 30.118 J Since it moves with constant speed.i.e., applied force =frcitonal force (c). we know kinetic frictional force = F cos [ mg - F sin ] = 7.418 Coeffcient of kinetic friction between the block and thefloor = 7.418 / [ mg - F sin 15 ] = 0.224