Springs and Stomachs

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In this demonstration, learners investigate mass, gravity, and acceleration by dropping a wooden bar with a balloon attached to its underside, a mass suspended from it by rubber bands, and a sharp-pointed screw pointing upward from the top of the mass. This activity also helps learners understand why stomach muscles feel uncomfortable and tense during a free fall or on a roller coaster. Learners can also explore this concept by dropping a slinky.

Quick Guide

Preparation Time:
10 to 30 minutes

Learning Time:
5 to 10 minutes

Estimated Materials Cost:
$5 - $10 per group of students

Age Range:
Ages 11 - 18

Resource Types:
Activity, Demonstration


Materials List (per group of students)

  • slinky
  • wooden bar
  • balloons
  • rubber bands
  • sharp-pointed screw
  • pillow, jacket, or other soft object (optional)
  • collection of steel washers
  • machine screw
  • wing nut
  • hot glue gun and hot glue
  • binder clip
  • adhesive-backed Velcro pieces
  • string


  • Life Sciences
    • Human Body
      • The Brain and Nervous System
      • Muscles and Skin
  • Physical Sciences
    • Motion and Forces
      • Gravity
      • Acceleration
    • Structure and Properties of Matter
      • Mass and Weight
  • The Nature of Science
    • The Scientific Process
      • Conducting Investigations

Informal Categories

  • Toys


To use this activity, learners need to:

  • see
  • hear
  • touch

Learning styles supported:

  • Involves hands-on or lab activities


This resource is part of:

Access Rights:

  • Free access


  • Rathjen, Don


  • All rights reserved, Exploratorium,