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In the Galileo’s Paradox and Hinged Stick vs. Falling Ball Demonstration Kit for physical science and physics, illustrate important concepts, such as torque, acceleration and center of mass with this discrepant event demonstration.

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In the blink of an eye, illustrate important concepts, such as torque, acceleration and center of mass with this discrepant event demonstration. A stick with a cup near one end and a hinge at the other is propped at an angle with a support rod. A ball is placed on the end of the stick so that the ball is below the lip of the cup. The support rod is swiftly pulled out, the ball and stick fall simultaneously, resulting in the ball landing in the cup! Did the stick really fall faster than the free-falling ball? After students study the apparatus they will recognize that the stick does not actually “free fall.” The stick rotates as it falls because of the hinge, and this causes the end of the stick to accelerate faster than its center of mass, allowing the end of the stick to beat the ball to the ground. This economically designed apparatus is easy to set up.

Concepts: Acceleration due to gravity, torque, rotational acceleration, center of mass.
Time Required: 15 minutes
Note: A support stand is required and available separately.

Correlation to Next Generation Science Standards (NGSS)

Science & Engineering Practices

Asking questions and defining problems
Developing and using models
Planning and carrying out investigations
Analyzing and interpreting data
Obtaining, evaluation, and communicating information

Disciplinary Core Ideas

MS-PS2.A: Forces and Motion
MS-PS3.A: Definitions of Energy
HS-PS2.A: Forces and Motion
HS-PS2.B: Types of Interactions
HS-PS3.A: Definitions of Energy
HS-PS3.B: Conservation of Energy and Energy Transfer
HS-PS3.C: Relationship between Energy and Forces

Crosscutting Concepts

Systems and system models
Energy and matter
Structure and function
Stability and change

Performance Expectations

MS-PS4-2: Develop and use a model to describe that waves are reflected, absorbed, or transmitted through various materials.
MS-LS1-3: Use argument supported by evidence for how the body is a system of interacting subsystems composed of groups of cells.
MS-LS1-8: Gather and synthesize information that sensory receptors respond to stimuli by sending messages to the brain for immediate behavior or storage as memories.
HS-LS1-2: Develop and use a model to illustrate the hierarchical organization of interacting systems that provide specific functions within multicellular organisms.