# Nature of Gravity and Free-Fall

Submitting Organization: Gooru

Subject Area: Science

Standards Alignment: Next Generation Science Standards

HS-PS2-4 Objective: Describe the nature of gravity on the surface of the Earth

Description of the Activity:

Try this activity from Summit Public Schools that simulates dropping an object from a tower (simulation here).  Change the height of the object and the acceleration of gravity and observe what happens.  By the time you finish this activity, you should be able to:

1.  Explain the difference between mass and weight.
2.  Describe the nature of gravity as an attractive non-contact force between two objects with mass (inverse square law).
3.  Describe the nature of gravity (free-fall) on the surface of earth.

Summit Public Schools have designed curricula comprised of project-based learning and focus areas, respectively designed to foster growth in interdisciplinary cognitive skills and facilitate mastery of content. Summit’s projects have been vetted by Stanford University’s SCALE program and focus areas align to Common Core State Standards. Summit’s high school courses are A-G approved in California.

Discussion Questions:

Before the simulation:

• If two objects with different masses are undergoing free fall, would they have equal acceleration? Why/why not?
• How do you think air friction will affect the objects?

After the simulation:

• What happened when you dropped various objects from the same height?  Why do you think that happened?
• How do mass and distance affect the gravitational force between two objects?
• What was the impact of increasing/decreasing mass and distance on the gravitational force between two objects? Was the gravitational force different/similar between various objects?  Why/why not?
• What observations can we then make about gravity on the surface of the earth?

Resources Needed:

• Four different sediment samples (e.g., sands, silts, unsorted sediment)
• Microscopes, slides, cover slips,
• Water and droppers
• Paper rulers
• A graph showing the relationship between particle diameter and stream velocity