9TH GRADE · CURVILINEAR MOVEMENT AND BALANCE
Circular dynamics and satellites
Centripetal force and first escape velocity.
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Basic Concepts
Centripetal force
This is the name for the resultant force directed towards the center and creating centripetal acceleration.
This is not a new special force: its role can be played by gravity, tension, friction, or the sum of them.
Artificial satellite
A body moves in orbit when gravity continuously imparts acceleration to it towards the center of the planet.
The satellite is in a long free fall and constantly misses the surface due to horizontal speed.
First escape velocity
The minimum speed of a circular orbit near the surface of a planet without taking into account the atmosphere and rotation.
For the Earth, the value is close to 7.9 km/s and is obtained from the equality of gravitational and centripetal accelerations.
Physical quantities
Centripetal force
Resultant force directed towards the center of the circle.
Unit: newton ·
First escape velocity
The speed of a circular orbit at the surface of the planet.
Unit: meter per second ·
Lesson formulas
Centripetal force
The resultant to the center is equal to the mass multiplied by the square of the velocity and divided by the radius.
First escape velocity
The speed of a circular orbit at the surface is equal to the square root of the product of g and the radius of the planet.
Related formulas
The same formulas in the reference, with symbols and units.
Tasks on the topic
Statements, answer options and the walkthrough.