Directions: Each of the questions or incomplete statements below is followed by five suggested answers or completions. Select the one that is best in each case and then fill in the corresponding circle on the answer sheet. Note: To simplify calculations, you may use g = 10 m/s^2 in all problems. Three distinct forces are applied to an object, but the object remains stationary. Which of the following must be correct? The forces have the same magnitude. The forces have the same direction. The forces are perpendicular to each other. The vector sum of the forces is zero. The sum of the magnitudes of the forces is zero. Which of the following is a true statement about the conservation of linear momentum? It is conserved only when no net external force acts on the system under consideration. It is conserved only when the center of mass of a system is at rest. It is conserved only in collisions between macroscopic objects. It is conserved only in two-body collisions. It is conserved only in one-dimensional and two-dimensional motion. A person of mass 60 kg sliding along level ice at a speed of 3.0 m/s collides with a second person who is initially at rest. Assume that friction is negligible. If the two people hold onto each other and their common final speed after colliding is 2.0 m/s, the mass of the second person is 1 kg 30 kg 40 kg 80 kg 90 kg An automobile travelling on a straight, level road has an initial speed v when the brakes are applied. In coming to rest with a constant acceleration, it travels a distance x. How far would the automobile travel in coming to rest if it had the same acceleration but an initial speed 2v? 1/4x. 1/2x x 2x 4x
