What Keeps Everything in Place in Space?

Questions to Ponder

• What forces keep the Earth in orbit around the Sun or the Moon in orbit around the Earth?

Activity A - Marble Motion

Materials

• 1 marble

• 1 transparent cup

• 1 tray

Question - How do objects move?

Procedures

1. Place the marble on the paper in the tray. Invert the plastic cup over the marble.

2. Move the cup in a rapid circular motion, causing the marble to move around the inside edge of the cup.

3. While the marble is moving rapidly in the cup, lift the cup straight up off the paper.

4. Record what you observed in your notebook.

5. Repeat the activity three more times, paying careful attention to the path of the marble after lifting the cup.

6. Describe the marble’s motion.

7. Draw an explanation of the marble’s motion in your journal; be sure to label the drawing. (Cup, Marble and Path of the marble)

Back to Teams...

1. What do all of the illustrations have in common?

2. What kept the marble moving in a circular pattern?

3. Inertia is an object’s resistance to a change in its motion.  This means objects at rest will stay at rest, and objects that are moving will continue to move in a straight line unless they are acted on by an unbalanced force.  How does the concept of inertia apply to this activity?

Activity B - Spinning Tennis Ball of Science

Materials

• tennis ball attached to a rope

Question - 

Procedure - Your teacher will hold one end of the rope and spin the tennis ball around.

1. Diagram - Draw what you see.  Label all of the parts.  Use arrows to demonstrate the movement that you observe.  How did the teacher's hand move while they were spinning the ball?  Label this on your diagram.

2. Predict - What do you think would happen if the teacher stopped moving the ball?  Draw a diagram to show what you think would happen.

3. Predict - What do you think would happen if the teacher let go of the rope?  Draw a diagram to show what you think would happen.

4. What forces were acting on the tennis ball?

5. Predict - Your teacher will now spin the ball and then stop spinning.  Describe what you think will happen to the ball.

6. Observe

7. Analyze -