9 Uniform motion is a constant velocity time period, which means you were traveling at a steady unchanging speed at any time. Uniform motion is when an object is travelling at a constant velocity. When velocity is constant then acceleration is zero. If a body has no acceleration, then the forces acting on it must be in equilibrium and so there must be a zero net force. 10 Displacement is the change in position while distance is the total displacement travelled. By reading the textbook I learned that gravitational potential energy depends on the height of an object not the path travelled. I conclude that gravitational potential energy depends on the displacement in y direction. Now I understand the distinction between distance and displacement. Displacement is the difference in where you start vs where you end, while distance is the total path covered. 11 Uniform motion is a pretty easy one to explain, in that it is the movement an objects makes in constant time without changing the position in each period of constant time and how fast it is going. Newton’s first law states that every object stays at rest or in uniform motion (motion in a straight line with constant speed and direction) unless a net external force acts on it. 12 Uniform motion is the rate at which an object moves at equal distances. It doesn’t mean that direction of motion is positive even if it is positive. A pendulum would be going in uniform motion because it is travelling the same distance every time. The key point is that if there is no net external force acting on an object and thus the object maintains a constant velocity. If that velocity is zero, then the object stays at rest. If the velocity is not zero, then the object maintains that velocity and moves in a straight line, which means the direction of motion is also constant.