KICKING AROUND THE PLANETS (2)

Educator Section – Note: This activity uses the same planetary grid as Activity one.
Introduction
Why does a soccer ball fall to Earth?
Why does the International Space Station orbit our planet, instead of flying off into the solar system?
Why do astronauts on board seem weightless?
It's perhaps the most famous "Eureka!" moment in science. The story goes that Isaac Newton was sitting in an orchard when suddenly. The impact of an apple on his head set him thinking about the force of gravity.
Newton hypothesized that every object exerts a pull on every other object. As you work alongside your friend in science class, his body is pulling him towards you... and yours is pulling you towards him. If you said that the pull of the Earth on both of you has more influence on your motion-or lack of it-than the pull of your respective bodies... you're right.
That's also why a soccer ball falls down to Earth. Even though the soccer ball also pulls up on the planet, the planet's mass is so much greater than the soccer ball, and mass-the amount of matter in an object-creates gravity.
The most noticeable force that shapes our solar system of course is gravity... gravity is what keeps all the planets in orbit around the sun. It’s what keeps us, glued down to the surface of the Earth. It makes you feel heavy when you stand on the bathroom scale... Now perhaps you think that the words "mass" and "weight" mean pretty much the same. In everyday life, that's ok, but not in science class.
Astronauts at Cape Canaveral walk out to the Shuttle. A few days later, they're up in humanity's first long-term home away from home. Is their mass the same in space as on Earth? Is their weight? Well, mass is defined as the amount of matter in an object so that's pretty much the same up in orbit as when they walked to the launch pad. As they float around in space they seem weightless. The key word is "seem." Weight is a measure of mass in a gravitational field: it's Earth's gravity which makes mass measurable on a scale.
Dribbling a soccer ball is a method individual players use to move the ball from one point to another while preventing the opposition from gaining possession of it. The purpose of dribbling is practically the same as passing, except that only one player physically deals with the ball. In essence, dribbling is advancing a ball by bouncing it or giving it a series of short kicks or pushing it. Every time the soccer ball is dribbled by a soccer player, the ball falls back down to Earth.
Lesson Objective
In this activity, students will learn that
1. Different sized balls are easier or harder to control and the size of the ball determines what degree of control that a player has when dribbling the soccer ball.
2. It is not the size of the planet (ball) but the distance of the planet from the sun that determines the rate at which it revolves around the sun.