I. A wooden block is at rest on a horizontal surface. If a 10 N force applied parallel to the surface is required to set the block in motion, the force required to keep the block moving at constant velocity is (a) less than 10 N, (b) greater than 10. N, (c) 10. N. Explain. 2. A constant unbalanced force of friction acts on a 15.0-kg mass moving along a horizontal surface at 10.0 m/s. If the mass is brought to rest in I .50 seconds, what is the magnitude of the force of friction? 3. A 1.0 *102-kg box rests on the bed of a tuck that is accelerating at 2.0 m/s?. What is the magnitude of the force of friction on the box as it moves with the tuck without slipping? 4. The diagram at right represents a block sliding down an incline. Redraw the picture and label all the forces acting on the block as represented by the drawn vectors. 5. As the angle e increases, what happens to the coefficient of kinetic friction between the surfaces in # 4. 6. A book weighing 20 Newtons slides at a constant velocity down a ramp inclined m. at 30 to the horizontal as shown in the diagram at right. Determine the force of friction between the two surfaces