Question

An electron moving along the x axis has a position given by x = 12te-4t m, where t is in seconds. How far is the electron from the origin when it momentarily stops?

Answer 1

When the particle stops, it's velocity is zero.

Hence, first take the derivative of the position equation to get the equation for velocity:

\[x' = v = dx/dt\]

Then set v = 0 and solve for t.

Finally, take what you found for t, and plug it into the position equation.