- #1

- 466

- 0

y = (t/SQRT(10) - 2ln(1+e^(t/SQRT(10)) - C) x 20SQRT10

## Homework Equations

## The Attempt at a Solution

Have tried many times to find value for t with little success help needed!

You are using an out of date browser. It may not display this or other websites correctly.

You should upgrade or use an alternative browser.

You should upgrade or use an alternative browser.

- Thread starter andrey21
- Start date

- #1

- 466

- 0

y = (t/SQRT(10) - 2ln(1+e^(t/SQRT(10)) - C) x 20SQRT10

Have tried many times to find value for t with little success help needed!

- #2

HallsofIvy

Science Advisor

Homework Helper

- 41,833

- 963

So you want to solve

y = (t/SQRT(10) - 2ln(1+e^(t/SQRT(10)) - C) x 20SQRT10

## Homework Equations

## The Attempt at a Solution

Have tried many times to find value for t with little success help needed!

[tex]20\sqrt{10}(\frac{t}{\sqrt{10}}- 2ln(1+ e^{\frac{t}{\sqrt{10}}})- C)= 0[/tex]

I would start by doing two things: divide both sides by [itex]20\sqrt{10}[/itex] and replace [itex]t/\sqrt{10}[/itex] by "u". Now the equation is

[tex]u- 2ln(1+ e^u)- C= 0[/tex]

Of course, you can't get a specific numerical result without a specic value for C. Even then I suspect that there will be no solution in terms of elementary functions.

- #3

- 466

- 0

y' = 20SQRT10 x (1-e^(t/SQRT10))/(1+e(t/SQRT10))

Where C is a constant of integration, is this correct? Becasue the question looks as if a specific numerical value must be found.

- #4

- 466

- 0

Anymore comments help needed please!!!!

- #5

Mark44

Mentor

- 34,884

- 6,621

Why would you take the derivative?

y' = 20SQRT10 x (1-e^(t/SQRT10))/(1+e(t/SQRT10))

Where C is a constant of integration, is this correct? Becasue the question looks as if a specific numerical value must be found.

The skydiver will be on the ground at the time when y = 0 in the equation in your first post. That's what HallsOfIvy was telling you in his reply. Did you read it?

Since no integration has apparently been done, C is not a constant of integration. Is there any other information in your problem that you haven't posted?

- #6

- 466

- 0

y = (t/SQRT(10) - 2ln(1+e^(t/SQRT(10)) - C) x 20SQRT10

I had to use seperation of variables and integration on the following:

y' = 20SQRT10 x (1-e^(t/SQRT10))/(1+e(t/SQRT10))

Which is the reason for the constant of integration C, try it yourself and see if you come up with the same solution as me. Only other information is that at y(0) = 4000.

Thanks

- #7

Mark44

Mentor

- 34,884

- 6,621

There's a reason for the three parts in the problem template, of which the first is the

y = (t/SQRT(10) - 2ln(1+e^(t/SQRT(10)) - C) x 20SQRT10

I had to use seperation of variables and integration on the following:

y' = 20SQRT10 x (1-e^(t/SQRT10))/(1+e(t/SQRT10))

Which is the reason for the constant of integration C, try it yourself and see if you come up with the same solution as me. Only other information is that at y(0) = 4000.

Thanks

- #8

- 466

- 0

- #9

Mark44

Mentor

- 34,884

- 6,621

Share: