Bell-Ringers

16 June 2009

Archimedes’ Lever

The Prediction

• “Give me a place to stand and a lever long enough and I will move the earth.”

• Do you think this is possible? Why or why not?

• Astronomers know the earth's mass. On earth a body possessing such a mass would weigh in round numbers

6,000,000,000,000,000,000,000 tons

• Supposing a man could lift only 60 kg directly, to "lift the earth" he would need a lever with a long arm that would be longer than the shorter arm by

1,000,000,000,000,000,000,000 times!!

• You can easily figure it out that to have the end of the short arm rise by one centimeter; the other end must describe through space the huge arc of

1,000,000,000,000,000,000 km

• Presuming Archimedes could have lifted 60 Kg one meter in one second- the work of almost one horsepower! - to lift the earth by just one centimeter, even then he would need

1,000,000,000,000,000,000,000 seconds

(30 million million years).

• Even if Archimedes had been able to push the lever with a speed of 0.34 km/sec the speed of sound, he would have lifted the earth by one centimeter only after

93,264,094,069,895.84265 years

• If he had pushed the lever with the speed of light, 300,000 km/sec, natures fastest possible- he would have lifted the earth by one centimeter only after ten million years of pushing.

Bell-Ringer

• 17 June 2009

• Learning Target: Explain how inclined planes make work easier.

• Name one inclined plane that you used today.

Bell-Ringer

• 17 June 2009

• Learning Target: Identify properties of polymers and metals.

• What is a “polymer”? What is a metal?