Escape Velocity vs Orbital Velocity
Escape velocity and orbital velocity are two very important concept involved in physics. These concepts are very important in fields such as satellite projects and atmospheric science. The escape velocity is the reason why we have an atmosphere and the moon doesn’t have one. It is vital to have a good understanding in these concepts in order to excel in relevant fields. This article will try to compare escape velocity with orbital velocity, their definitions, calculations, similarities and finally differences.
As we know from the gravitational field theory, an object having a mass always attracts any other object which is placed in a finite distance from the object. As the distance increases the force between the two objects lowers with the inverse square of the distance. At infinity, the force between the two objects is zero. The potential of a point around a mass is defined as the work that has to be done to bring an object of unit mass from infinity to the given point. Since there is always an attraction the work has to be done is negative; therefore, the potential at a point is always negative or zero. Potential energy is the potential multiplied by the mass of the object brought. The escape velocity is defined as the velocity that has to be given to an object in order to send it to infinity without any other force. In terms of energy, the kinetic energy due to the given velocity is equal to the potential energy. By this equality, we get the escape velocity as the square root of (2GM/r). Where r is the radial distance to the point the potential is measured.
The orbital velocity is the velocity an object must maintain in order to be on a certain orbit. For an object going on an orbit with radius r, the orbital velocity is given by the square root of (F r / m) where F is the net inward force and m is the mass of the orbital object. The inward force in a mass system is GMm/r2. By substituting this, we get the orbital velocity as the square root of (GM/r). This also can be proved using mechanical energy conservation of a conservative field. It must be noted that the orbital velocity is changing the direction. Therefore, this actually is acceleration, but the magnitude of the speed does not change. Small energy losses in space cause this kinetic energy to be reduced, and then the object comes to a lower orbit in order to stabilize.
What is the difference between Escape Velocity and Orbital Velocity?
• Escape velocity is the velocity that is required to escape from a surface.
• Orbital velocity is the velocity required to keep an object in an orbit.
• Both of these quantities are independent of the moving object.
• The escape velocity will reduce as the object reaches infinity and at infinity the velocity will be zero.
• The orbital speed remains constant throughout the orbit. The orbital velocity changes direction.