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Skills WorksheetINTEGRATING SPACE SCIENCE

Cross-Disciplinary

Gravity and the Planets

Read the following paragraphs, and complete the exercises below.

All the planets in the solar system, along with their moons, are affected by gravity in how they relate to one another in space. The closer two planets are to each other, the greater the effect of gravity on them. The force of gravity is also stronger on planets of greater mass.

Gravity keeps a planet in its orbit

The planets stay in their orbits because of the force of gravity that the sun and the other planets exert on each other. Nineteenth-century astronomers used their knowledge of gravity to predict the existence of the planet Neptune before it was discovered. In studying the motion of the planet Uranus, astronomers found an effect that could not be explained by the gravitational pull from Saturn and the other planets. They concluded that a more distant planet had to be responsible for this effect, and in 1846, Neptune was discovered near its predicted location.

Exercises

1.If identical objects were dropped simultaneously from a height of 2 m onEarth, Mars, and the moon, on which would the object reach theground first? Second? Explain your answer. (On Earth, g = 9.8 m/s2; on Mars,g= 3.7 m/s2;and on the moon,g= 1.6 m/s2.)

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2.Ellis, Mario, and Monique each begin jumping on identical brand new trampolines. Ellis is on Earth, Mario is on Mars, and Monique is on the moon. Individually, each person weighs 50 kg (110 lb), spacesuit included. Which astronaut will be able to jump the highest? Explain your answer.

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3.Which astronaut will free fall back onto the trampoline first? Explain your answer.

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Original content Copyright © by Holt, Rinehart and Winston. Additions and changes to the original content are the responsibility of the instructor.

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