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Week 2 Motion and Energy

Week 2 Motion and Energy - Motion and Energy Motion |...

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Motion and Energy Motion | Newton's Laws | Energy | Conclusion | Practice Quiz Please note , all words that are bold are rollovers that will display additional text in the form of a pop-up box. Motion Motion is all around us, and everything, extremely fast or stationary, is in motion. In the Week 1 lecture we looked at densities of materials and discovered that that all particles are in motion to one degree or another. Even solids are made up of particles that are in motion ( vibrational, rotations, and translational) although the motion is too slow for our eyes to perceive. View the video below for an explanation of the molecular movement within a gas. Density The two important aspects of motion are change in position and the passage of time. As such, the motion of an object is generally described with respect to an outside reference(or referent ), moving or not. Speed is the ratio of distance traveled to the time that has elapsed to cover that distance, and it is expressed as speed = distance/time. In the following illustration, a car moving in a straight line over a distance of 1 mile each minute is traveling at a rate of 60 mph. Velocity is often used interchangeably with speed; however, because velocity includes both speed and direction, there is a distinct difference. To affect a change in velocity, the speed, the direction, or both are changed. As shown below, velocity (v) can be represented as the ratio of the change in distance (d) to the change in time (t) or . The change in velocity and time are combined to create acceleration, or the rate at which motion changes. As shown below, acceleration is expressed as the change in velocity over the elapsed time . Force is a push or pull that is capable of changing the state of motion of an object. When two forces are parallel in the same direction, the net force is added. When two parallel forces are in opposite directions, the net force is the difference between the two forces, and it is in the direction of the larger force. When two or more forces act in entirely different directions, a new direction and strength is created. See the figure below. According to the text, there are four fundamental forces that cannot be explained in terms of any other force. They are: gravitational: which are the forces that act between all objects including objects in space electromagnetic: which are the forces acting between electrically charged particles weak nuclear: which are the forces involved in certain nuclear reactions strong nuclear: which are the forces involved in close-range holding of the nucleus together. These fundamental forces are responsible for everything that happens in the universe including electricity, light, nuclear energy, and chemical, geological, and astronomical phenomena.
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The last term we will discuss is inertia . Inertia is the tendency of an object to remain in a state of unchanging motion, moving or at rest, with a net force of zero. As shown in the figure below, a satellite moving through space will travel at a constant speed in a straight path (A) until a force is applied against the direction of motion (B). Force
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Week 2 Motion and Energy - Motion and Energy Motion |...

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