On average, a male polar bear generally weighs about 770 to 1,500 pounds, but have been weighed in once at a high more than 1,760 pounds. The average female weighs anywhere from 330 to 720 pounds, sometimes breaking 1,000 pounds while pregnant. ... A tall and built structure is not something that comes quickly to the polar bear, for when they are born they weigh less than a kilogram and are only about twenty-five centimeters long. ... The polar bear continues to live its life mating, hunting, and changing until it reaches the mid to late twenties where their life usually ends. ... In the...

• Word Count: 1651
• Approx Pages: 7
• Grade Level: High School

Current ion engines use xenon as fuel, but the overall design of the engines has not changed since the 1950's. ... DS1 used 72 kilograms xenon propellant that operated for 16,246 hours, and the spacecraft is currently orbiting the sun with the radio transmitters so future generations can contact DS1. ... This engine's output is approximately 1/50th of a pound of thrust with a consumption of about 2500 watts of electricity (?). ... The fuel capacity for DS1, for example, is only 178 pounds. ...

• Word Count: 1766
• Approx Pages: 7
• Grade Level: High School