Posted by Marcus on .
A proton is put on the positive Y axis a large distance (100km) from the origin. What is the minimum speed required in the  Y direction so the proton will just reach the point (0,20) cm?

College Physics 
Damon,
Is there some sort of repelling positive charge at the origin or what ?
If so the kinetic energy at infinity has to equal the potential energy at 20 cm 
College Physics 
Marcus,
0,0 is the origin there is no repelling charge

College Physics 
Damon,
Then there is no force on the proton and it will keep going forever with infintesimal velocity.

College Physics 
Marcus,
So what's the minimum speed ?