<p>The question comes from Princeton Review and it is:
The velocity of a particle of charge +4.0x10^-9 C and mass 2x10^-4kg is perpendicular to a 0.1 tesla magnetic field. If the particle’s speed is 3x10^4 m/s, what is the acceleration of the particle due to the magnetic force?
The answer is choice C) 0.06 m/s^2 and the book sets F=ma and solves for a. (using qvB as F)
But according to princeton review: “Magnetic Forces cannont change the speed of an object, only its direction” so why isnt the answer choice e)None of the above. <= i.e. 0</p>
<p>u should pay attention to the definition of “acceleration” It means the how fast velocity changes either in direction or magnitude. Princeton review whats to tell u magnetic forces only change the direction of the velocity but not its magnitude (i.e. speed) by giving the object a centripetal acceleration. </p>
<p>So, there’s nothing wrong for an acceleration that affects the direction only.</p>