How come "terminal velocity" and "final velocity" are different?

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SUMMARY

The discussion clarifies the distinction between terminal velocity and final velocity in the context of a bullet shot perpendicular to the ground with air resistance. Terminal velocity is defined as the maximum speed an object can achieve when the net force acting on it is zero, primarily due to air resistance. In contrast, the final velocity can be less than terminal velocity if the bullet does not have sufficient time to reach terminal velocity before hitting the ground. The equations provided illustrate the relationship between initial velocity, terminal velocity, and the effects of air resistance on the bullet's motion.

PREREQUISITES
  • Understanding of Newton's laws of motion
  • Familiarity with concepts of velocity and acceleration
  • Knowledge of air resistance and its mathematical representation
  • Basic proficiency in solving differential equations related to motion
NEXT STEPS
  • Study the derivation of terminal velocity in fluid dynamics
  • Explore the effects of varying air resistance coefficients on projectile motion
  • Learn about the mathematical modeling of motion under gravity and resistance
  • Investigate real-world applications of terminal velocity in different contexts
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Physics students, educators, and anyone interested in understanding the dynamics of projectile motion and the effects of air resistance on velocity.

Ted goldmund lee
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Homework Statement



Someone shot the bullet perpendicular to the ground. And there is air resistance.
Velocity of bullet is
v^2 = Ae^(-2kx)-g/k upward
v^2 = g/k-Be^(2kx) downward

A,B is constant, g is a gravitational acceleration, k = c2/m , c2 is a resistance constant, m is a mass of bullet.

When air resistance is C2v^2 show that final speed of the bullet is

VoVt/Root(Vo^2+Vt^2) , Vo is initial velocity and Vt is terminal velocity.

Homework Equations



I thought that terminal velocity is the velocity when there is no net force on the object.
Since there is no parasutre, shouldn't the final velocity is same with terminal velocity?
How come final velocity is smaller than terminal velocity...
( I am pretty sure in this question we don't have to consider air density )

The Attempt at a Solution



upload_2019-2-27_23-46-25.png

I did solve this mathmetically but I just don't understand the physical concept.
How can something be slower when net force on it is zero.
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Ted goldmund lee said:
Since there is no parasutre, shouldn't the final velocity is same with terminal velocity?
Terminal velocity is the fastest it can go due to air resistance. Final velocity may be less if it hits the ground before making it all the way up to terminal velocity.
 
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