Activity 4 Newton's Laws of Motion Problem: To extricate an SUV stuck in the mud, workmen Aqure F4.2 use three horizontal ropes, producing the force vectors shown in Fig. E4.2. (a) Find the x- and y components of each of the three pulls. (b) Use the components to find the magnitude and direction of the resultant of the three pulls. Problem: A 68.5-kg skater moving initially at 2.40 m/'s on rough horizontal ice comes to rest uniformly in 3.52 s due to friction from the ice. What force does friction exert on the skater? 3 Problem: An astronaut's pack weighs 175 N when she is on the earth but only 3.24 N when she is at the surface of a moon. (a) What is the acceleration due to gravity on this moon? (b) What is the mass of the pack on this moon? 4 Problem: Boxes A and B are in contact on a horizontal, frictionless surface (Fig. E4.23), Box A Figure E4.23 has mass 20.0 kg and box B has mass 5.0 kg A horizontal force of 250 N is exerted on box A. What 250 N is the magnitude of the force that box A exerts on box B? Problem: A chair of mass 120 kg is sitting on the horizontal floor; the floor is not frictionless. You push on the chair with a force F - 40.0 N that is directed at an angle of 37.0" below the horizontal, and the chair slides along the floor. (a) Draw a clearly labeled free body diagram for the chair. (b) Use your diagram and Newton's laws to calculate the normal force that the floor exerts on the chair