Velocity as a function of distance problem

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Homework Help Overview

The problem involves determining the force, position, and time functions for a ball whose velocity varies with distance, described by the equation v(x) = ax-n. The subject area includes dynamics and calculus, particularly focusing on the relationships between velocity, acceleration, and distance.

Discussion Character

  • Exploratory, Mathematical reasoning, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the relationship between velocity and distance, with one noting confusion regarding the dependence of velocity on distance rather than time. Others suggest using the chain rule to relate acceleration to distance and time, and propose integrating to find expressions for position and acceleration.

Discussion Status

Some participants have offered guidance on integration techniques and relationships between variables, while others are exploring different interpretations of the problem. There is an ongoing exchange of ideas, with attempts to clarify the integration process and derive the necessary functions.

Contextual Notes

Participants are navigating the complexities of integrating a velocity function that is dependent on distance, which may not align with typical approaches that assume time dependence. There is also mention of specific constants and variables that may influence the integration process.

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Homework Statement



The velocity of a ball of mass 'm' varies with the distance v(x) = ax-n, where a and n are positive constants.

Determine F(x), x(t) and F(t).

Homework Equations


F = ma
a = dv/dt
v = dx/dt


The Attempt at a Solution


If velocity were the function of time, i would have done it with no problem. I determined the acceleration, which is -nax-n-1.
For v, i integrated 'a' with respect to t. But velocity's dependence in distance confused me. Any help will be highly appreciated.
 
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There is a simple way for these.
a=dv/dt. This can be written as a=dx/dt*dv/dx.
 
v = dx/dt = a*x^-n
So x^n*dx = a*dt.
Find the integration and then find x in terms of a, n and t.
Then d^2(x)/dt^2 will give acceleration in terms of a,n and t. from that you can find F(t)
Acceleration a = dv/dt = dv/dx*dx/dt = dv/dx*v. Then F(x) = ma
 
Last edited:
To rl.bhat

Thanks. I tried to follow your instruction.
Integration of x^n*dx = a*dt gave me (1/n+1)x^(n+1) = v. I didn't find x in terms of a, n and t.
 
(1/n+1)x^(n+1) = v.
This should be
(1/n+1)x^(n+1) = at
x^(n+1) =a(n+1)*t
x = ...?
 

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