# Homework Help: Finding time it takes for electron to travel a certain distance

1. Jun 18, 2014

### GoGoGadget

1. The problem statement, all variables and given/known data
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?

2. Relevant equations

d = 1/2(v0 + v)t

3. 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.

2. Jun 18, 2014

### haruspex

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

3. Jun 18, 2014

### 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....

Last edited: Jun 18, 2014
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