http://www.cleancartalk.com/battery-technology-hybrid-electric-cars/converting-fossil-fuel-energy-to-battery-energy/ Hybrid, Electric, Plug-in, Clean Diesel Cars for the Responsible Consumers. Thu, 09 Feb 2012 13:27:45 +0000 hourly 1 http://wordpress.org/?v=3.3.1 http://www.cleancartalk.com/battery-technology-hybrid-electric-cars/converting-fossil-fuel-energy-to-battery-energy/#comment-673 Tom Bartley Thu, 21 Apr 2011 09:04:37 +0000 http://www.cleancartalk.com/?p=1177#comment-673 You’re right about the units. E=½mv2 But F=ma, where a=g if F=weight. Substituting, E=½(F/g)v2 . If I use the units of lbs for F; 32 ft/sec2 for g, the acceleration of gravity; and feet/sec for v, the speed; the result is E=(weight/64) x (Speed)2 in units of ft-lbs(force) of energy. 2,655,200 ft-lb(f) = 1 kWh Using your Prius numbers of 3000 lbs and 30 mph (44 ft/sec) E = (3000/64) x (44)2 = 90,750 ft-lb(f) = 0.03418 kWh = 34.18 Wh Coincidentally, the 30 mph energy is nearly equal to the 30 ft elevation gravity energy of 90,000 ft-lb(f) = 0.03390 kWh = 33.90 Wh The 30 feet elevation and 30 mph energy equivalence works for a vehicle of any weight. So if freeway on ramps all headed downhill you would get a free 30 mph. Conversely, if you were going 30 mph heading up a freeway exit ramp you would stop at the top without using your brakes. At 60 mph the distance is 4 x 30 = 120 feet because of the velocity squared factor. You’re right about the units. E=½mv2 But F=ma, where a=g if F=weight. Substituting, E=½(F/g)v2 . If I use the units of lbs for F; 32 ft/sec2 for g, the acceleration of gravity; and feet/sec for v, the speed; the result is E=(weight/64) x (Speed)2 in units of ft-lbs(force) of energy. 2,655,200 ft-lb(f) = 1 kWh
Using your Prius numbers of 3000 lbs and 30 mph (44 ft/sec)
E = (3000/64) x (44)2 = 90,750 ft-lb(f) = 0.03418 kWh = 34.18 Wh
Coincidentally, the 30 mph energy is nearly equal to the 30 ft elevation gravity energy of 90,000 ft-lb(f) = 0.03390 kWh = 33.90 Wh
The 30 feet elevation and 30 mph energy equivalence works for a vehicle of any weight. So if freeway on ramps all headed downhill you would get a free 30 mph. Conversely, if you were going 30 mph heading up a freeway exit ramp you would stop at the top without using your brakes.
At 60 mph the distance is 4 x 30 = 120 feet because of the velocity squared factor.

]]> http://www.cleancartalk.com/battery-technology-hybrid-electric-cars/converting-fossil-fuel-energy-to-battery-energy/#comment-672 skierpage Tue, 19 Apr 2011 21:17:31 +0000 http://www.cleancartalk.com/?p=1177#comment-672 Google coughed up your page and it's OK as an overview of the different kinds of energy. But your formula "Energy = (Weight/64) x (Speed)²" is useless and wrong without units! Why divide by 64?! I know E = ½mv² , I was hoping to find a nifty JavaScript calculator that tells me a 3000 pound Prius moving at 30 mph has X kW·h of kinetic energy. Wikipedia's Kinetic energy article and Google's awesome "3000 lb in kg", "30 mph in m/s" instant conversions suggest that X is 0.03 kW·h. Google coughed up your page and it’s OK as an overview of the different kinds of energy. But your formula “Energy = (Weight/64) x (Speed)²” is useless and wrong without units! Why divide by 64?! I know E = ½mv² , I was hoping to find a nifty JavaScript calculator that tells me a 3000 pound Prius moving at 30 mph has X kW·h of kinetic energy. Wikipedia’s Kinetic energy article and Google’s awesome “3000 lb in kg”, “30 mph in m/s” instant conversions suggest that X is 0.03 kW·h.

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