Find the acceleration, velocity and position

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Discussion Overview

The discussion revolves around a physics homework problem involving the motion of a sprinter. Participants are tasked with finding the acceleration, velocity, and position of the sprinter under the influence of a constant horizontal force and air resistance. The problem is framed within the context of numerical solutions.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Technical explanation

Main Points Raised

  • One participant calculates the initial acceleration as a1 = 400N/80kg but seeks assistance in determining the velocity (v).
  • Another participant questions the meaning of the term a1*t in the context of the equations presented.
  • A later reply suggests using initial acceleration conditions and differential equations to derive a logarithmic function of velocity over time, and subsequently to find position as a function of time.
  • One participant indicates that the problem can only be solved numerically and asks for insights on numerical methods taught in class.
  • Another participant mentions they will post their solution later, indicating ongoing contributions to the discussion.

Areas of Agreement / Disagreement

Participants express differing views on how to approach the problem, particularly regarding the use of numerical methods versus analytical solutions. There is no consensus on a single method or solution at this stage.

Contextual Notes

The discussion includes assumptions about the applicability of numerical methods and the specific forms of equations used, which may depend on the definitions and conditions set by the problem. The mathematical steps leading to the proposed solutions remain unresolved.

Who May Find This Useful

This discussion may be useful for students studying dynamics, particularly those interested in numerical methods for solving motion problems involving forces and resistances.

MaxManus
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Homework Statement


The motion of a sprinter with
mass = 80 Kg
the sprinter is accelerated with a constant horizontal force: 400 N
The air resistance is 0.5*p*Cd*A*(v-w)**2
p = 1.293 kg/m**3
Cd = 1.2
A = 0.45 m**2
v = velocity
w = 0 m/s

find the acceleration, velocity and position

The Attempt at a Solution


a1 = 400N/80kg

a(t) = a1*t - (1/m)*0.5*p*Cd*A*(v)**2

Can someone help me with the v?
I am allowed to solve it numerically
 
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MaxManus said:

Homework Statement


The motion of a sprinter with
mass = 80 Kg
the sprinter is accelerated with a constant horizontal force: 400 N
The air resistance is 0.5*p*Cd*A*(v-w)**2
p = 1.293 kg/m**3
Cd = 1.2
A = 0.45 m**2
v = velocity
w = 0 m/s

find the acceleration, velocity and position

The Attempt at a Solution


a1 = 400N/80kg

a(t) = a1*t - (1/m)*0.5*p*Cd*A*(v)**2

What is the a1*t term supposed to represent?

Can someone help me with the v?
I am allowed to solve it numerically
I think this one can only be solved numerically. What have you been taught so far about that? There are many different ways to solve it numerically, it would be good if you can tell us what your professor or textbook says about this.
 
Solved, I will post my solution later.
 
Use initial acceleration condition and differential equations to solve the problem you geta logarithimic function of velocity with time..now again use same to get position as a function of time .
 

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