You tie the rope to the stake, and then you give the ball a push.And the ball's gonna take this circular path on the table when we view it from the side.And when a rope pulls, we call that the force of tension, so I'm gonna call this the tension. Now we know what kind of force is acting as the centripetal force. Sometimes, people want to do this, they're like, oh yeah, there's a force of tension, and there's also a centripetal force.
And then you use Newton's second law for one of the directions at a time.
And if the direction you chose to analyze Newton's second law for didn't get you to where you needed to be, just do it again.
The centripetal force is just an extra title we give to a force that happens to point toward the center of the circle, but how would I ever solve a problem like this? I've got forces that are up, that are down, that are in. Let's say the mass of the ball was two kilograms, the rope's length was 0.5 meters, and the ball is traveling around the circle at a constant speed of five meters per second.
So let me show you how to solve some problems and some things to keep in mind. So what kind of question might you be asked if given a problem like this?
The secret to solving centripetal force problems is that you solve them the same way you solve any force problem.
In other words, first, you draw a quality force diagram.So saying the force that causes this ball to go in a circle is the centripetal force is a little unsatisfying.It'd be like answering the question, what force balances the force of gravity while the ball's on the table with the answer, the upward force.A possible question would be, well, what's the force of tension in the rope?And so, now's a good time for me to let you in on a little secret.I mean, it's gotta be either the force of friction or normal force or tension or the force of gravity.The centripetal force isn't a new type of force.- [Instructor] There are unfortunately quite a few common misconceptions that many people have when they deal with centripetal force problems, so in this video, we're gonna go over some examples to give you some problem solving strategies that you can use as well as going over a lot of the common misconceptions that people have when they deal with these centripetal motion problems.So, to start with, imagine this example, let's say a string is causing a ball to rotate in a circle.We've got forces, but they're kind of all over here.This side view's gonna better illustrate all the forces involved.