STEVE EMBER: Newton was able to find the exact relationship between distance and gravity. He multiplied the mass of one space object by the mass of the other. Then he divided that number by the square of their distance apart. The result was the strength of the gravity force that tied them to each other.
Newton proved his idea by measuring how much gravity force would be needed to keep the moon orbiting the Earth. Then he measured the mass of the Earth and the moon, and the distance between them. He found that his measurement of the gravity force produced was not the same as the force needed. But the numbers were close.
Newton did not tell anyone about his discovery. He put it aside to work on other ideas. Later, with correct measurements of the size of the Earth, he found that the numbers were exactly the same.
SHIRLEY GRIFFITH:Newton spent time studying light and colors. He used a three-sided piece of glass called a prism.
He sent a beam of sunlight through the prism. It fell on a white surface. The prism separated the beam of sunlight into the colors of a rainbow. Newton believed that all these colors -- mixed together in light -- produced the color white. He proved this by letting the beam of rainbow-colored light pass through another prism. This changed the colored light back to white light.
STEVE EMBER: Newton's study of light led him to learn why faraway objects seen through a telescope do not seem sharp and clear. The curved glass lenses at each end of the telescope acted like prisms. They produced a circle of colored light around an object. This created an unclear picture.
最新
2013-11-25
2013-11-25
2013-11-25
2013-11-25
2013-11-25
2013-11-25