Physics and the Solar System

Check the Moon Phase What is the moon phase called today? What is the position of the moon in its orbit around the Earth?

Challenge Questions Earn a quiz grade by writing as much as you can in 3 minutes What is an orbit? What shape are orbits? What force keeps planets from escaping the Sun? What force keeps planets from crashing into the Sun?

Glossary Gravity- The force of attraction between all objects. Inertia- The force of an object in motion. Velocity- The speed an object is travelling.

Newton’s 1st Law… Isaac Newton was a scientist who revolutionized physics. He discovered that an object in motion stays in motion unless it meets with an opposite and equal force. The force of the object in motion is called inertia.

Newton’s Balls Each of you will get a pair of Newton’s balls. Swing Newton’s balls correctly, and one ball will appear to change color How can you explain this using Newton’s 1st law?

Explanation One ball appears to stay in place because when it swings it meets with “an opposite and equal force”- another ball with the same mass. What would happen if the balls were different sizes?

Differential Forces Inertia is calculated by multiplying the mass of an object by its velocity. This is written as: T = mv or inertia = mass x velocity

Extension Lunar landing Try to balance the thrust of a lunar lander against the force of the moon’s gravity.

Agenda Read pages 446 & 447: Science A Closer Look Answer planetary motion questions Add new vocabulary to glossary Classroom illustration of inertia and gravity Calculating inertia