[Physical Science:] Finding Kinetic Energy

AI Thread Summary
To find the mass of an alpha particle with a given kinetic energy of 6.0 x 10^-13 J and speed of 1.6 x 10^7 m/s, the formula K.E. = 0.5 * m * v^2 can be rearranged to solve for mass. For the electron moving at 2.5 x 10^8 m/s, the classical kinetic energy formula is also applicable, though relativistic effects may need consideration due to its high speed. The discussion emphasizes the importance of using scientific notation for clarity in calculations. Participants express confusion about applying the formulas and converting numbers correctly. Understanding the relationship between kinetic energy, mass, and velocity is crucial for solving these problems.
Jessi
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Two homework problems I don't understand. :(

9. An alpha particle travels at 1.6 x 10^7 m/s. The kinetic energy of the particle is 6.0 x 10^-13 J. What is the mass of the alpha particle?

I think scientific notation is supposed to be used, so "1.6 x 10^7" is 16,000,000 and "6.0 x 10^-13" is .0000000000006, but I still don't know what to do with the numbers.

10. An electron with a mass of 9.0 x 10^-31 kg moves through a vacuum with a speed of 2.5 x 10^8 m/s. Find the electron's kinetic energy.

Again, I'm guessing "9.0 x 10^-31" is .0000000000000000000000000000009 and "2.5 x 10^8" is 250000000, so does that make the answer 2.8125 x 10^-14
 
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Kinetic Energy is found by the equation

K.E. = .5 *m* v^2

where m = mass and v = velocity
 
You may want to use the relativistic formula for the second case,though,it's roughly 83% of the speed of light...

Daniel.

P.S.And yes,please use scientific notation...Nobody will be willing to count the zeros...
 
I'm given the kinetic energy - how do I find the mass?

Dexter, I'm sorry..I didn't understand anything that you said. I don't think I'm familiar with the relativistic formula. I'm guessing what I did was wrong, then? :P
 
Okay,no problem,then don't use it.Use the classical one.Extract mass,knowing the KE and velociy.A mere division...

Daniel.
 
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