Can u help with this problem?

 

 

A charged particle of mass 1.50 g is moving at a

speed of 1.50 3 104 m/s. Suddenly, a uniform magnetic

field of magnitude 0.150 mT in a direction perpendicular

to the particle's velocity is turned on and then turned off in

a time interval of 1.00 s. During this time interval, the magnitude

and direction of the velocity of the particle undergo a negligible change,

but the particle moves by a distance of 0.150 m in a direction perpendicular

r to the velocity. Find the charge on the particle.

 

I know that qvb=ma

The only unknown to get q is a. How to get it ?

 

Also I am confused, of how it is mentioned that change of velocity is negligible and there is acceleration ? shouldn't a be zero ?

Smells like homework to me...

studying for the final

I can't be sure what the writer of the question intended. My guess would be that the intent is that the change in direction can be ignored in terms of kinematics. IOW, you can simplify this to a 1D kinematics problem; given an acceleration you have a certain displacement, and it's a clumsy way of getting a new and different equation for acceleration into the problem.