Answer and discuss each problem in a detailed way.

1. A 2.50 kg box is pulled by a constant force of 16 N that is exerted at an angle 36.90 above the horizontal. The box has moved a distance of 3.00 m along a horizontal surface whose coefficient of kinetic friction is 0.21. (a) What is the total work done on the box? (b) What is the speed of the box at 3.00 m if it is initially at rest? 2. Two blocks A (WA=12 N) and B (WB=20 N) are connected by very light string that passes over a frictionless pulley (as shown in Figure 3.8). Block B rest 20 N on top of a horizontal tabletop and has a coefficient of kinetic friction against between of 0.15. Block A is suspended on the other end and it does not hit the edge of the tabletop. When the system is released from rest, block A descends to 75 cm. (a) What is the total work done on the system? 12 N (b) Using work-energy theorem, what is the speed of each blocks as block A descends to 75 cm? Fig. 3.8