# An electron moving along the x axis has a position given by x = 18 te-t m, where t is in seconds. How far is t?

An electron moving along the x axis has a position given by x = 18 te^-t m, where t is in seconds. How far is the electron from the origin when it momentarily stops?

Do I have to find the derivative and solve for zero?

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- DouglasLv 78 years agoBest answer
Yes.

You are given x(t) = 18te^-t

You compute x'(t)

Set x'(t) = 0

Solve for the value of t when the velocity is zero.

Then substitute that value of t into x(t) to find the electron's position when it momentarily stops

- billrussell42Lv 78 years ago
yes, the derivative would be speed or velocity, and when it momentarily stops the derivative would = 0

So you differentiate, set x' = 0, solve for t, and substitute that value of t back in the original equation to get distance.

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