Introduction to Engineering. Energy

Transcription

1 Introduction to Engineering Energy

2 Chapter 3, Part A 3.1 A Serious Predicament 3.2 Systems, Surroundings and Interaction 3.3 Work and Power 3.4 The Heat Interaction 3.5 Energy - A Property of Matter 3.6 Kinetic Energy 3.7 Potential Energy 3.8 Internal Energy 3.9 Mass and Energy are Conserved 3.10 Limitations on Energy Conversion Efficiency

3 Chapter 3, Part A 3.1 A Serious Predicament 3.2 Systems, Surroundings and Interaction 3.3 Work and Power 3.4 The Heat Interaction 3.5 Energy - A Property of Matter Sections in RED are specifically to be READ!!! 3.6 Kinetic Energy 3.7 Potential Energy 3.8 Internal Energy 3.9 Mass and Energy are Conserved 3.10 Limitations on Energy Conversion Efficiency

4 Chapter 3, Part A 3.1 A Serious Predicament 3.2 Systems, Surroundings and Interaction 3.3 Work and Power 3.4 The Heat Interaction 3.5 Energy - A Property of Matter Sections in RED are specifically to be READ!!! 3.6 Kinetic Energy 3.7 Potential Energy 3.8 Internal Energy 3.9 Mass and Energy are Conserved 3.10 Limitations on Energy Conversion Efficiency

5 Chapter 3, Part B 3.11 Organic Fuels Natural Gas and Oil Coal Oil Shales and Tar Sands Energy through Bioconversion 3.12 Solar Energy Solar Collection Surfaces The Solar Pond Ocean Solar Energy Converters Solar Cells 3.13 Energy from the Wind

6 Chapter 3, Part B 3.11 Organic Fuels Natural Gas and Oil Coal Oil Shales and Tar Sands Energy through Bioconversion 3.12 Solar Energy Solar Collection Surfaces Sections in RED are specifically to be READ!!! The Solar Pond Ocean Solar Energy Converters Solar Cells 3.13 Energy from the Wind

7 Work and Power Work can be described as a Force operating through a distance.

8 Work and Power Work can be described as a Force operating through a distance. Therefore, Work = Force times distance or W = F d

9 Work and Power Work can be described as a Force operating through a distance. Therefore, Work = Force times distance or W = F d If F is in Newtons (N) and distance is in Meters (m), then the unit for work is a Newton-meter (N-m), but

10 Work and Power Work can be described as a Force operating through a distance. Therefore, Work = Force times distance or W = F d If F is in Newtons (N) and distance is in Meters (m), then the unit for work is a Newton-meter (N-m), but

11 Work and Power Work can be described as a Force operating through a distance. Therefore, Work = Force times distance or W = F d If F is in Newtons (N) and distance is in Meters (m), then the unit for work is a Newton-meter (N-m), but

12 Work and Power Work can be described as a Force operating through a distance. Therefore, Work = Force times distance or W = F d If F is in Newtons (N) and distance is in Meters (m), then the unit for work is a Newton-meter (N-m), but Therefore, 1 N-m = 1 Joule

13 Work and Power (cont.) Power is Work done per unit time or the time rate of doing work.

14 Work and Power (cont.) Power is Work done per unit time or the time rate of doing work. If W is Power, then

15 Work and Power (cont.) Power is Work done per unit time or the time rate of doing work. If W is Power, then

16 Work and Power (cont.) Power is Work done per unit time or the time rate of doing work. If W is Power, then If W is in Newton-meters or Joules and time is in seconds, then the unit for Power is a Newtonmeter/s or J/s, which is a Watt (W)

17 Work and Power (cont.) In the English System, Work is in ft lbf Power is in ft lbf/s and 550 ft lbf/s = 1 Horsepower

18 Examples 1) Given a 400N block a) Compute the work required to raise it to a height of 3 m. b) If it took 50s to complete the task, how much power was expended? 2) A motor driving a winch lifts 1 metric ton to a height of 10m in 20s. Assuming NO friction and 100% efficiency, how much Horsepower does the motor produce? (1 hp = 746 W)

19 Examples 1) Given a 400N block a) Compute the work required to raise it to a height of 3 m N-m or 1200 J or 1.2 kj b) If it took 50s to complete the task, how much power was expended? 2) A motor driving a winch lifts 1 metric ton to a height of 10m in 20s. Assuming NO friction and 100% efficiency, how much Horsepower does the motor produce? (1 hp = 746 W)

20 Examples 1) Given a 400N block a) Compute the work required to raise it to a height of 3 m N-m or 1200 J or 1.2 kj b) If it took 50s to complete the task, how much power was expended? 24 W or kw 2) A motor driving a winch lifts 1 metric ton to a height of 10m in 20s. Assuming NO friction and 100% efficiency, how much Horsepower does the motor produce? (1 hp = 746 W)

21 Examples 1) Given a 400N block a) Compute the work required to raise it to a height of 3 m N-m or 1200 J or 1.2 kj b) If it took 50s to complete the task, how much power was expended? 24 W or kw 2) A motor driving a winch lifts 1 metric ton to a height of 10m in 20s. Assuming NO friction and 100% efficiency, how much Horsepower does the motor produce? (1 hp = 746 W) hp

22 More Examples 3) Calculate the work done by: a) lifting a 20kg box to a height of 6m. b) pushing on a brick wall with a force of 60N. c) You walking up a 15m set of stairs (1 kg = 2.2 lbs)

23 More Examples 3) Calculate the work done by: a) lifting a 20kg box to a height of 6m N-m or 1176 J 0r kj b) pushing on a brick wall with a force of 60N. c) You walking up a 15m set of stairs (1 kg = 2.2 lbs)

24 More Examples 3) Calculate the work done by: a) lifting a 20kg box to a height of 6m N-m or 1176 J 0r kj b) pushing on a brick wall with a force of 60N. 0 N-m or 0 J 0r 0 kj c) You walking up a 15m set of stairs (1 kg = 2.2 lbs)

25 More Examples 3) Calculate the work done by: a) lifting a 20kg box to a height of 6m N-m or 1176 J 0r kj b) pushing on a brick wall with a force of 60N. 0 N-m or 0 J 0r 0 kj c) You walking up a 15m set of stairs (1 kg = 2.2 lbs) For me, N-m or J 0r kj

26 Even more Examples 4) Calculate the power expended by: a) lifting a 60kg box to a height of 8m in 4s. b) placing 10 1kg books from a 1m high shelf to a 2m high shelf, one at a time, in 20s. c) You running up a 25m set of stairs in 10s (1 kg = 2.2 lbs and 746W = 1hp) in Watts, in kilowatts and in Horsepower.

27 Even more Examples 4) Calculate the power expended by: a) lifting a 60kg box to a height of 8m in 4s. 1176W or 1.176kW b) placing 10 1kg books from a 1m high shelf to a 2m high shelf, one at a time, in 20s. c) You running up a 25m set of stairs in 10s (1 kg = 2.2 lbs and 746W = 1hp) in Watts, in kilowatts and in Horsepower.

28 Even more Examples 4) Calculate the power expended by: a) lifting a 60kg box to a height of 8m in 4s. 1176W or 1.176kW b) placing 10 1kg books from a 1m high shelf to a 2m high shelf, one at a time, in 20s. 4.9 W c) You running up a 25m set of stairs in 10s (1 kg = 2.2 lbs and 746W = 1hp) in Watts, in kilowatts and in Horsepower.

29 Even more Examples 4) Calculate the power expended by: a) lifting a 60kg box to a height of 8m in 4s. 1176W or 1.176kW b) placing 10 1kg books from a 1m high shelf to a 2m high shelf, one at a time, in 20s. 4.9 W c) You running up a 25m set of stairs in 10s (1 kg = 2.2 lbs and 746W = 1hp) in Watts, in kilowatts and in Horsepower. For me, W or kW or 3.36hp

30 Note: What is a kw-h?

31 Note: What is a kw-h?

32 Note: What is a kw-h? Therefore a kw-h is a unit of Work!!!

33 Assignment

34 Assignment p ,