Inverse-square force laws are the focus of this Grade 9 Science worksheet on gravity and electrostatics, giving students practice with how force magnitude changes with distance and how force direction depends on the interaction.

Students work with quantitative inverse-square models, including the relationship between force and the square of separation distance. They apply proportional scaling to predict changes without recalculating every value, such as recognizing that doubling distance reduces an inverse-square force to one-fourth and that tripling distance reduces it to one-ninth. The resource also connects magnitude with vector reasoning, including attractive gravitational forces and attractive or repulsive electrostatic forces.

What students practice

• Match key definitions related to gravitational and electrostatic force laws.
• Complete a cloze reading passage using vocabulary such as inverse-square, attractive, repulsive, like charges, and unlike charges.
• Label a force diagram and interpret force direction between interacting objects.
• Read an explanatory passage about point masses, point charges, separation distance, force magnitude, and vector direction.
• Apply multiple-choice reasoning to satellite gravity, charge relationships, point-mass approximations, net force, and distance scaling.
• Evaluate true-or-false statements about inverse-square relationships, gravitational direction, electrostatic attraction and repulsion, and vector addition.
• Give concise written answers involving distance factors, gravitational attraction, and electrostatic force direction.
• Write an extended response explaining how inverse-square laws predict both force magnitude and direction for gravity and electrostatic interactions.

Built for classroom use

Use the worksheet as independent practice, guided classwork, review, or a lesson check within a Grade 9 unit on forces and interactions. The progression from definitions and reading to diagram labeling, selected-response reasoning, concise responses, and extended explanation gives students multiple ways to apply the same core concepts.

Teacher support included

A separate Teacher Guide PDF is included with learning objectives, teaching tips, discussion questions, and common mistakes. This gives teachers practical support for introducing inverse-square relationships, prompting discussion about force direction, and addressing misconceptions as students work through the material.

The resource is aligned to the NGSS framework named for this lesson and centers on the specific relationship between distance and force in gravitational and electrostatic interactions.