Uniform rectilinear movement
Testing the hypothesis of a Galilean benchmark in practical life
Autor:
Título 4
Learning objectives :
This activity allows students to understand the concept of Galilean frame of reference and uniform rectilinear motion. It develops the ability to experimentally verify the conditions of an ideal movement.
Concepts covered
Uniform rectilinear movement; Galilean reference frame; Zero acceleration; Inertia; Principle of relativity
What students will do :
The student uses FizziQ sensors to test whether it is possible to maintain a uniform rectilinear movement while walking. By recording acceleration or GPS position data during a movement in a straight line, the student analyzes the graph obtained to determine if the movement is truly uniform and then reflects on the difficulties and the most appropriate instruments to achieve and verify this type of movement.
What is required :
Smartphone with the FizziQ application; A clear outdoor space for walking in a straight line; FizziQ experience notebook
Scientific background :
Uniform rectilinear motion (MRU) is characterized by a straight line trajectory and constant velocity, which implies zero acceleration. It is the natural movement of a body when no force is exerted on it, as Newton formulated it in his first law (principle of inertia). A frame of reference in which this principle is verified is called a Galilean frame of reference. This experiment allows you to explore these fundamental concepts of classical mechanics. To check if a movement is uniform rectilinear, several FizziQ sensors can be used: 1) The accelerometer: in a perfect MRU, the acceleration should be zero. Any variation indicates acceleration or deceleration; 2) GPS: by tracing the position over time, we can check the linearity of the movement and the constancy of the speed. In practice, performing a true MRU while walking is surprisingly difficult because human walking is naturally oscillatory and jerky. Each step involves a phase of acceleration and deceleration. This difficulty illustrates why perfect MRUs are rare in nature and generally limited to brief periods. The Galilean principle of relativity states that the laws of mechanics are identical in all Galilean frames of reference. This explains the strange sensation evoked in the activity: in a high-speed MRU train, we do not "feel" the movement because all the physical laws apply there exactly as in a stationary frame of reference. It is only the acceleration that we perceive, hence the strangeness of the moments when we have the impression of being still even though we are moving at high speed. This experience thus makes it possible to make the link between a fundamental theoretical concept and a daily sensory experience.