Posted by **Brian** on Wednesday, December 12, 2012 at 9:30pm.

How much work must be done to increase the speed of an electron (a) from 0.18c to 0.19c and (b) from 0.98c to 0.99c? Note that the speed increase is 0.01c in both cases.

- Physics -
**drwls**, Wednesday, December 12, 2012 at 11:10pm
Total energy is

E(rest) + E(kin)

= m*c^2/sqrt[1 - (v/c)^2]

Calculate that at each speed and take the difference.

(a) m*c^2/sqrt[1 - .19^2]

- m*c^2/sqrt[1 - .18^2]

= m*c^2[1.01855 - 1.01660]

= m*c^2* 1.95*10^-3

- Physics -
**Brian**, Thursday, December 13, 2012 at 12:38am
I got 1*10^-16 but what's the unit for my answer? Because the book says 1.0 ke V is the answer for part (a). How do I get there?

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