240 likes | 340 Views
Ch 8. Feb 24. http:// www.youtube.com/watch?v=rMBpuQMj1Qw. RECAP - In addition to…. Work Energy Theorem. In addition to…. Work Energy Theorem And the different types of PE & KE. In addition to…. Work Energy Theorem And the different types of PE & KE
E N D
Ch 8 Feb 24
RECAP - In addition to… • Work Energy Theorem
In addition to… • Work Energy Theorem • And the different types of PE & KE
In addition to… • Work Energy Theorem • And the different types of PE & KE • There is one more MAIN CONCEPT for today…
Conservation of Energy Example: Energy transforms without net loss or net gain in the operation of a pile driver. Ch07 - Energy - Revised: 2/21/10
Conservation of Energy Part of the PE of the wound spring changes into KE. The remaining PE goes into heating the machinery and the surroundings due to friction. No energy is lost.
Conservation of Energy Everywhere along the path of the pendulum bob, the sum of PE and KE is the same. Because of the work done against friction, this energy will eventually be transformed into heat.
But you need to complete it!!! KE = ½ (15 kg) (10 m/s)2 Using GERMDOS, there are a few ways to manipulate the numbers to get to the correct answer. I think the easiest way is this: KE = (7.5 kg) (100 m2/s2) KE = 750 kg m2 s2 KE = 750 J
Complete the next 2! 750 J 3000 J* Notice – we doubled the velocity (compared to #1)…did the KE double? 1500 J* Notice – we doubled the velocity (compared to #1)… …did the KE double?
PE = mgh PE = (1 kg)(10 m/s2)(0m) PE = 0 J
PE = mgh PE = (1 kg)(10 m/s2)(0m) PE = 0 J PE = mgh PE = (10 kg)(10 m/s2)(-4m) PE = -400 J
PE = mgh PE = (1 kg)(10 m/s2)(0m) PE = 0 J PE = mgh PE = (10 kg)(10 m/s2)(-4m) PE = -400 J PE = mgh PE = (15 kg)(10 m/s2)(-7m) PE = -1050 J
Go back… And finish this entire packet!!! (including the page we skipped) Anything not done in class is HOMEWORK! Check in at STOP SIGNS!
Your HW • Finish today’s notes – the ENTIRE PACKET. • Due at the start of next class!!! • Read & Study 670-672. Complete #1-7 on p. 672 • (write FULL Q & A – they are typed on website if you prefer!) • Also, finish today’s notes if you don’t during class! • Ch 8 test on March 4 • Study guide is online this afternoon, and will be passed out on Wednesday
EXIT SLIP Finish the last column & back of your Do Now – turn in! Turn paper over