3 ms·
"both a stick of butter and an SUV traveling at 100 mph contain about a kilowatt-hour of energy" How's that?
by chrisweekly 4y ago
"both a stick of butter and an SUV traveling at 100 mph contain about a kilowatt-hour of energy"
How's that?
- Cerium 4y agoThe stick of butter is easy: it contains about 800 kilo-calories. This can be converted to 0.94 kWh: (calories)(joules per calorie)(watts = joules/second)(kw = 1000w) Kinetic energy is 1/2(v*v^2) The average SUV weighs about 2000 Kg. That yields about 0.55 KWh. Perhaps the parent used a larger SUV.
- chrisweekly 4y agoIt still seems bonkers to me. What if the SUV slowed to a stop, standimg at rest beside the stick of butter. Which represents more potential energy?
- Cerium 4y agoBesides the gas in the tank the car has zero potential energy at a stop. All the kinetic energy was lost to heating the brakes.
- frankus 4y agoThe parent forgot the 1/2. So more like 140 mph (or a heavier vehicle).