Question to find air resistance

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SUMMARY

The discussion focuses on calculating the work done by air resistance on a body of mass m dropped from a height without initial velocity. The initial attempt used the equation E_(final) - E_(initial) = W_net, leading to an incorrect expression for force. The correct formula for the force exerted by air resistance is established as F = 0.5mv(gt - v), where g represents gravitational acceleration. This highlights the importance of accurately applying the laws of conservation of momentum and inertia in physics problems involving air resistance.

PREREQUISITES
  • Understanding of Newton's laws of motion
  • Familiarity with the concepts of work and energy in physics
  • Knowledge of gravitational acceleration (g)
  • Basic algebra for manipulating equations
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  • Study the principles of air resistance and drag force in fluid dynamics
  • Learn about the conservation of energy in mechanical systems
  • Explore the derivation of the equations of motion under the influence of gravity and air resistance
  • Investigate the application of calculus in solving physics problems involving variable forces
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Students studying physics, particularly those focusing on mechanics and dynamics, as well as educators looking for examples of air resistance calculations in real-world scenarios.

siddharthmishra19
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Homework Statement



A body of mass m is dropped from a certain height without initial velocity. At the time t when its speed is v, what is the work done by the air resistance to retard the body?

Homework Equations



Laws of conservation of momentum and inertia

The Attempt at a Solution



[tex]E_(final) - E_(initial) = W_net[/tex]

[tex]mv^2/2 - mgh = Fs = Fvt[/tex]

Solving,

[tex]F = (mv^2/2 - mgh)vt[/tex]

Something is definitely wrong... the answer is given as:

[tex]F = 0.5mv(gt-v)[/tex]
 
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siddharthmishra19 said:

Homework Statement



A body of mass m is dropped from a certain height without initial velocity. At the time t when its speed is v, what is the work done by the air resistance to retard the body?

Homework Equations



Laws of conservation of momentum and inertia

The Attempt at a Solution



[tex]E_(final) - E_(initial) = W_net[/tex]

[tex]mv^2/2 - mgh = Fs = Fvt[/tex]

Solving,

[tex]F = (mv^2/2 - mgh)vt[/tex]

Something is definitely wrong... the answer is given as:

[tex]F = 0.5mv(gt-v)[/tex]

s would be vt if the body moved with constant velocity v during the time t.
The work done by the air resistance is Fh, where F is the mean value of the air resistance.
 

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