(adsbygoogle = window.adsbygoogle || []).push({}); [SOLVED] Simple Kinetic energy problem

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

A proton travelling at 23 degrees with respect to the direction of a magnetic field of strength 2.6mT experiences a magnetic force of 6.5*10^-17 N. Calculate a) the proton's speed and b) its kinetic energy in electron-volts

2. Relevant equations

For part a) I simply used F=qvbsin(theta), I got the correct answer of 400,000m/s

For part b) I used K = 0.5*m*v^2

3. The attempt at a solution

For part b) I plugged in the value of 9.1*10^-31 for m and the value of v I found above(400,000m/s). I return 7.28*10^-20 (assume this in in J?). Upon conversion to eV I find a measly 0.45eV. (The answer is 835ev!)

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# Homework Help: Simple Kinetic energy problem

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