00:03
So there are a couple approaches for this problem.
00:07
Let's start with just writing down everything that we're given.
00:10
We have a mass, m.
00:17
It is equal to 6 .6 times 10 to the minus 27 kilograms.
00:41
27.
00:44
And it's a good idea to keep track of si units.
00:50
Make sure we don't need to convert anything.
00:52
This is in kilograms, which is in units that are si, so that's good there.
00:56
We are given the velocity of this traveling mass is 4 .4 .4 times 10 to the fifth.
01:27
And velocity is given in meters per second.
01:30
Also, si, units.
01:31
Don't need to convert anything there.
01:38
We are given a magnetic field that this particle is in.
01:44
B.
01:45
That is equal to 0 .75 tesla.
01:58
That's also si unit for magnetic field, so we don't need to change anything.
02:02
And lastly, we're given a radius, this particle, this mass is traveling in a circle, so we are given a radius, little r.
02:14
Now this is .012, and this is in meters, also si units.
02:21
That's good.
02:22
We don't need to change anything right off the bat.
02:24
So, now another point to note before we start doing any of the math for this problem is that everything that we're given has two significant figures.
02:39
So that's what we'll want to keep all of our answers to.
02:42
We'll want to have two significant figures.
02:45
So now, as i said at the beginning, there are two approaches to this problem.
02:49
One of them is a little bit more complicated.
02:53
Let's write out the equations that we have.
02:56
So we have that the force, the centripetal force, f sub c, is equal to, this is mass times velocity square.
03:18
Divided by the radius.
03:21
Now, centripetal force is the force that keeps it traveling in a circle.
03:26
If there was no centripetal force, it would just fly off straight instead of continuing to travel in a circular motion.
03:34
That's what this force is, and we know that this is caused by this magnetic field...