00:01
All right, so let's say we have a block moving in a circle about the origin, and we're told at a particular instant in time, it has a position vector of 2 .89 meters j -hat.
00:14
So that's basically the radius of our circle.
00:17
It's 2 .89 meters, and it's subject to a magnetic field of 1 .48 tesla in the y direction, or z direction, excuse me, so we'll point that this way.
00:28
All right, so this is the direction of our magnetic field, and the block has a charge of 2 .48 kulamps.
00:36
We're told its velocity at this instant is given us 6 .49 meters a second i -hat.
00:44
So it's traveling this way.
00:47
And so we want to know what is the tension in the rope.
00:51
So if we draw, the centripetal force on the block, which is going to be mv squared over r, is going to point this way.
00:59
In fact, let me draw this in red.
01:01
So this is our tension, and our centripetal force goes the same direction...