Parabolic flight
Simulate weightlessness with a parabolic flight using a smartphone
Autor:
Titre 4
Learning objectives :
This activity allows students to understand the phenomenon of weightlessness by simulating a parabolic flight with their smartphone. It develops the understanding of free fall movement and the effects of gravity.
Concepts covered
Free fall; Weightlessness; Inertial frames of reference; Parabolic movement; Equivalence principle
What students will do :
The student uses the FizziQ accelerometer to record the acceleration during a parabolic motion. By gently throwing his smartphone above a mattress and analyzing the acceleration data, the student observes that during the free flight phase the measured acceleration is close to zero despite the constant presence of gravity, which allows us to understand the principle of apparent weightlessness.
What is required :
Smartphone with the FizziQ application; A mattress or soft surface to securely hold the smartphone; A clear space; FizziQ experience notebook
Scientific background :
The parabolic flight experiment simulates on a small scale the phenomenon used by "Zero-G" aircraft to create temporary weightlessness conditions. This phenomenon is based on a fundamental principle of physics: an object in free fall does not "feel" gravity. A smartphone's accelerometer measures not gravity directly, but the reaction force that the mount exerts on the device. When resting on a table, it detects an upward acceleration of approximately 9.8 m/s², corresponding to the normal force opposing the weight. When the smartphone is thrown into the air, it enters into free fall under the exclusive influence of gravity. In this non-inertial frame of reference (the smartphone itself), all objects appear to be floating, because they experience exactly the same acceleration. This is why the accelerometer indicates a value close to zero during the free flight phase. It's not that gravity has disappeared, but rather that its effects can no longer be measured by an accelerometer free-falling with it. This phenomenon illustrates Einstein's principle of equivalence, the foundation of general relativity: it is impossible to locally distinguish between a gravitational effect and an equivalent acceleration in the opposite direction. Planes carrying out parabolic flights for astronaut training or scientific experiments follow precisely this trajectory: they climb sharply nose-up, then reduce the thrust of the engines to follow exactly the natural trajectory of a body in free fall for 20-25 seconds, creating perfect weightlessness inside. Likewise, the International Space Station is constantly in free fall around the Earth, hence the state of permanent weightlessness of its occupants, despite a gravity still equal to approximately 90% of that on the earth's surface at this altitude (400 km).