More Physics help..... Which formulas should i use??? thankssssssssss 1. Three forces act on a moving object. One force has a magnitude of 86.3 N and is directed due north. Another has a magnitude of 67.0 N and is directed due west. What must be (a) the magnitude and (b) the direction of the third force, such that the object continues to move with a constant velocity? Express the direction as an angle with respect to east. 2. The drawing shows a circus clown who weighs 772 N. The coefficient of static friction between the clown's feet and the ground is 0.545. He pulls vertically downward on a rope that passes around three pulleys and is tied around his feet. What is the minimum pulling force that the clown must exert to yank his feet out from under himself? *** click on the link for pic**** http://publish.hometown.aol.co.uk/hyen84/images/untitled.bmp [Broken] 3. A person is trying to judge whether a picture (mass = 1.74 kg) is properly positioned by temporarily pressing it against a wall. The pressing force is perpendicular to the wall. The coefficient of static friction between the picture and the wall is 0.71. What is the minimum amount of pressing force that must be used? 4. A skier is pulled up a slope at a constant velocity by a tow bar. The slope is inclined at 31.0° with respect to the horizontal. The force applied to the skier by the tow bar is parallel to the slope. The skier's mass is 49.9 kg, and the coefficient of kinetic friction between the skis and the snow is 0.232. Find the magnitude of the force that the tow bar exerts on the skier.