Yeah, infinity.

Electricity and Magnetism Level 2

Two identical point charges Q A = Q B = Q Q_A = Q_B = Q have the same mass.

If initially B is at rest at x = 0 x=0 and A is located at x = − ∞ x=- \infty and moving toward B with speed v 0 v_0 , then what is the speed of B when A is located at x = 0 x=0 ?

v 0 v_0 v 0 / 4 v_0 /4 v 0 / 2 v_0 /2 2 v 0 2v_0

Kelvin Hong by Kelvin Hong , 21, Malaysia

This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try refreshing the page, (b) enabling javascript if it is disabled on your browser and, finally, (c) loading the non-javascript version of this page . We're sorry about the hassle.

2 solutions

Donglin Loo
Jan 8, 2018

The solution can be viewed as the vice versa of the original question as when A reach the position of B, A and B repel. Die to the fact that A and B are identical(same mass and same charge), B starts moving towards infinity just like when A moves from infinity towards B with the same speed(different velocity due to direction) . My solution may not be the most scientific one but hope it is appreciated.

p/s:This is a good use of symmetry frequently applied in Mathematics. By the way, I also participated in this contest and have come across this question too.

1 Helpful 0 Interesting 0 Brilliant 0 Confused
Kelvin Hong
Aug 27, 2017

This isn't a solution

I get this question from NCKU Year 2016 Mathematical Contest.

Hopefully somebody write a full solution to this.

Appreciate that.

0 Helpful 0 Interesting 0 Brilliant 0 Confused

0 pending reports

×

Problem Loading...

Note Loading...

Set Loading...