Finding time it takes for electron to travel a certain distance

[GoGoGadget]

Homework Statement

Over a distance of 3 cm an electron accelerates uniformly from a speed of 9 x 10³ m/s to a speed of 6 x 10⁶ m/s. How long does it take the electron to cross this distance?

Homework Equations

d = 1/2(v₀ + v)t

The Attempt at a Solution

Find t:

d = 3 cm /10 cm = 0.3 m
2 d / v₀ + v = t

2 (0.3 m) / (9 x 10³ m/s + 6 x 10⁶ m/s) = t

This is where I got a little lost, especially with trying to do it on paper as I'm not able to use a calculator for the test.

 

[haruspex]

d = 3 cm /10 cm = 0.3 m

Umm.. how many cm to the m?

2 (0.3 m) / (9 x 10³ m/s + 6 x 10⁶ m/s) = t

This is where I got a little lost, especially with trying to do it on paper as I'm not able to use a calculator for the test.

First, there's a simple cancellation out of a factor. If you then write out the denominator in fixed point, what do you notice?

 

[bobie]

Average speed is V = 600900000/2 =300450000 cm
time is 3 /V = 3/30045 (*10000) can you do 3.00000/30045 on paper? and then 0.00000000...