1. Day 45, Thursday, 29 October, 2015 Steam Engines Quick Review (Energy) Steam Engines Power Angular Momentum

2. Quick Review Law of Conservation of Energy Energy is conserved in a closed and isolated system (no forces or matter going in or out) Every time it looks like it is gained or lost, it has been accounted for “Perpetual Motion Machines” do not exist

3. Mechanical Energy ME = KE + U g (if no other forms of energy are present) Energy is Conserved KE before + U g before = KE after + U g after

4. Path Independent Free fall slide down a wedge Circular curve (such as a pendulum) Roller Coaster

5. Potential Energy to Kinetic Energy to Work In a steam engine Potential energy in Fuel (chemical) Kinetic Energy in flame [thermal – 1/2mv 2 (micro)] Kinetic Energy in Steam [thermal – 1/2mv 2 (micro)] Heat is transferred from flame to steam Kinetic Energy in Piston (translational) Steam pushes on piston [1/2mv 2 (macro)] Work (force on piston moves it a distance) W = Fd Waste Heat [kinetic (thermal)]

6. Steam Engines

10. Power P = W/t Power is work divided by time Power is measured in watts A watt is a joule per second [(kg) (m/s 2 ) (m/1)] / s = (kg m 2 )/s 3

11. F = ma W = FdW = mad P = W/t P = (mad)/t N = kg m/s 2 J = kg m 2 /s 2 W = kg m 2 /s 3

12. Power Power = work/time The unit of power is a watt (W) one watt = 1 joule per second P = W/t P = (Fd)/t P = Fv

13. Horsepower

14. 1 horsepower is equivalent to 746 watts. So if you took a 1- horsepower horse and put it on a treadmill, it could operate a generator producing a continuous 746 watts.

15. Angular momentum is conserved Radius vs. speed demo

17. Credits Steam Engine 1 www.unb.ca/web/transpo/mynet/steam eng.gif www.unb.ca/web/transpo/mynet/steam eng.gif Watt Steam Engine people.csp.edu/.../Watt%20steam%20e ngine.jpg

18. More Credits Steam Engine animation upload.wikimedia.org/wikipedia/commo ns/3/30/S... Newcomen Steam Engine www.unb.ca/web/transpo/mynet/newco men.gif

19. Ever More Credits Horsepower graphic http://auto.howstuffworks.com/horsepowe r.htm http://auto.howstuffworks.com/horsepowe r.htm