9TH GRADE · KINEMATICS
Free fall, circle and relativity
Fall, centripetal acceleration and relativity of speed.
The entire theory of the lesson is collected here; you can read it without an account. In interactive mode, the same theory appears as cards, followed by questions. with checking the answer and task, and progress is saved.
Basic Concepts
Uniform movement around a circle
Movement with a constant speed module, but a continuously changing direction of the speed vector.
Centripetal acceleration is directed towards the center and is responsible precisely for the rotation of the velocity vector.
Free fall
The movement of a body is only under the influence of gravity with negligible resistance of the medium.
In one place, all bodies receive the same g; it is measured by the time and path of fall or by the period of the pendulum with an estimate of the error.
Relativity of speed
The speed of the body depends on the reference system and is added to the portable speed of the selected system.
The passenger's speed relative to the ground is equal to the vector sum of his speed in the carriage and the speed of the carriage.
Physical quantities
Acceleration of free fall
Acceleration of a body when moving only under the influence of gravity.
Unit: meters per second squared ·
Trajectory radius
The distance from the center of the circle to the moving body.
Unit: meter ·
Centripetal acceleration
Acceleration directed towards the center of curvature of the trajectory.
Unit: meters per second squared ·
Lesson formulas
Centripetal acceleration
Centripetal acceleration is equal to the square of the velocity divided by the radius.
Related formulas
The same formulas in the reference, with symbols and units.
Tasks on the topic
Statements, answer options and the walkthrough.