# Physics

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.

1. 👍 0
2. 👎 0
3. 👁 374
1. 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

1. 👍 0
2. 👎 0
posted by drwls
2. 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?

1. 👍 0
2. 👎 0
posted by Brian
3. You should have got 1.6*10^(-16) as your answer - Which is the value of 1keV.

1. 👍 0
2. 👎 0
posted by Teacher

## Similar Questions

1. ### Physics

The Nuclues of a Manganese atom has a net charge of +4E-18C. Its nearest electron is located 4E-10 m from the nucleus. What is the electrostatic force between the nucleus and the electron? (Hint:what is the charge of the electron?

asked by Jill on February 22, 2010
2. ### physics

How much work must be done to increase the speed of an electron from 0.200c to 0.210c? In (MeV)

asked by Andy on April 14, 2010
3. ### Physics - urgent

I already asked this and was given an answer, but I don't fully understand it and so would like a further explanation. What I asked was... An electron is accelerated through a uniform electric field of magnitude 2.5x10^2 N/C with

asked by Linn on April 21, 2009
4. ### physics

An electron is accelerated from rest through a potential difference that has a magnitude of 2.90 × 107 V. The mass of the electron is 9.11 × 10-31 kg, and the negative charge of the electron has a magnitude of 1.60 × 10-19 C.

asked by PLEASE AND THANK YOU on April 4, 2013
5. ### Physics

An electron is accelerated through a uniform electric field of magnitude 2.5x10^2 N/C with an initial speed of 1.2x10^6 m/s parallel to the electric field. a) Calculate the work done on the electron by the field when the electron

asked by Linn on April 21, 2009
6. ### Physics - important

An electron is accelerated through a uniform electric field of magnitude 2.5x10^2 N/C with an initial speed of 1.2x10^6 m/s parallel to the electric field. a) Calculate the work done on the electron by the field when the electron

asked by Linn on April 21, 2009
7. ### Physics

An electron strikes the back of a TV screen at 1/10 the speed of light. What is the speed of the electron? What is the momentum of the electron? What is the deBrogile wavelength of the electron?

asked by Dana on April 7, 2008
8. ### Algebra 2

Need help on the #13-20. 13. What is the quotient of d − 2 ) d 4 − 6d 3 + d + 17 __________________ ? A. d 3 − 4d 2 − 8d − 15 R −13 B. d 3 − 8d 2 + 16d − 31 R 79 C. d 3 − 4d 2 + 9d + 35 D. d 3 − 8d 2 + 17d −

asked by Emily on December 6, 2010
9. ### Physics

Zinc has a work function of 4.30 ev . A 4.50eV photon strikes the surface and an electron is emitted. What is the maximum possible speed of the electron?

asked by paige on November 28, 2011
10. ### Chemistry

The photoelectric work function of a metal is the minimum energy needed to eject an electron by irradiating the metal with light. For calcium, this work function equals 4.34 x 10-19 J. If light with a wavelength of 256 nm impinges

asked by Piper on February 4, 2017

More Similar Questions