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Energy & Its Impact on Global Society

Energy & Its Impact on Global Society. Jerome K. Williams, Ph.D. Saint Leo University Dept. Mathematics & Sciences. Chapter 2: Energy Mechanics. Critical Thinking in Science Forms of Energy Primary Energy Souces & Energy Conversions Motion. Critical Thinking in Science.

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Energy & Its Impact on Global Society

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  1. Energy & Its Impact on Global Society Jerome K. Williams, Ph.D. Saint Leo University Dept. Mathematics & Sciences

  2. Chapter 2: Energy Mechanics • Critical Thinking in Science • Forms of Energy • Primary Energy Souces & Energy Conversions • Motion

  3. Critical Thinking in Science • Scientists seek to understand the physical world and how it works • Making Observations • Formulating Hypothesis • Testing Hypothesis by Experimentation

  4. Critical Thinking in Science • A tentative statement that tries to generalize a series of observations is a hypothesis. • A hypothesis that has been supported by a large number of observations and experiments is called a theory.

  5. Forms of Energy • Mechanical Energy • Two Kinds • Kinetic Energy (KE) – energy of motion • Potential Energy (PE) –energy of position

  6. Forms of Energy

  7. Forms of Energy • Chemical Energy – use fossil fuels & food for energy • Nuclear Energy- energy found in atomic nucleus • Thermal Energy: transfer heat between objects • Electrical Energy – energy produced at power plants or stored in batteries • Light (Radiant) Energy – also called electromagnetic radiation (ER); this covers a wide range of sources from radio and TV waves to X-rays and solar energy

  8. Primary Energy Sources & Energy Conversions • Primary Energy Sources • Chemical • Nuclear • Radiant • Energy Conversion Processes are how primary energy sources are converted to an end use (powering a car, heating a home, using a laptop computer, etc.)

  9. Primary Energy Sources & Energy Conversions

  10. Motion • Speed = distance traveled per unit time • Velocity = similar to speed except it must include direction of travel • Acceleration = change in velocity per unit time

  11. Motion

  12. Motion • Force = push or pull on an object by other objects in environment • Newton’s 2nd Law of Motion = acceleration of an object is directly proportional to the net force acting on it and inversely proportional to the object’s mass

  13. Motion • Units for Speed: • Examples m/s, km/h, ft/s, mph • Units for Force: • Examples Newton (N), Pound (lb) • Conversion Factors: 1 lb = 4.45 N • Table 2.4

  14. Example Problem 2.1 • A 2000 kg car is acted on by a force of 6000 N by its wheels. Also acting on the car is a force of friction of 800 N. What is the car’s acceleration? • Answer: 2.6 m/s2

  15. Example Problem 2.2 • Brakes are applied to a 1900 kg car moving at 80 km/h. In a time of 4.0 seconds, its velocity decreases uniformly to 30 km/h. What is the net force acting on the car? • Answer: 6650 N

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