Quick Motion Question (1 Viewer)

[sanzach]

A falling body experiences both the gravitational acceleration g and air resistance that
is proportional to its velocity. Thus a typical equation of motion is x(double dot) = −10 − 2v m/s^-2 .
Suppose that the body is dropped from the origin.

By writing x(double dot) = dv/dt and taking reciprocals, find t as a function of v, and hence find v
as a function of t. Then find x as a function of t.

I understand what it's asking but don't know where my error is in the integration.

 

[Squar3root]

did you get t = -1/2ln(20v +100)


I'm probably wrong lel

 

[kawaiipotato]

A falling body experiences both the gravitational acceleration g and air resistance that
is proportional to its velocity. Thus a typical equation of motion is x(double dot) = −10 − 2v m/s^-2 .
Suppose that the body is dropped from the origin.

By writing x(double dot) = dv/dt and taking reciprocals, find t as a function of v, and hence find v
as a function of t. Then find x as a function of t.

I understand what it's asking but don't know where my error is in the integration.

 

[braintic]

The velocity starts at zero and heads towards -5 ..... I thought you said this question was about quick motion ? .......

 

[sanzach]

Thanks for this, didnt correctly find the constant of integration.

 

[sanzach]

Sorry dude, i think you misinterpreted the title there... I meant it as in a speedy question, not referring to anything other than basic motion.

 

[braintic]

Sorry dude, i think you misinterpreted the title there... I meant it as in a speedy question, not referring to anything other than basic motion.

And ..... I think you didn't notice that my tongue was firmly planted in my cheek.