Here the magnitude of velocity is not changing because tangential acceleration is zero. But it's direction is changing because there normal acceleration which is also called as centripetal acceleration.
The weight of the person is actually directed straight down at all times. Where as the angle of the normal force changes if it is a ball on a pivot. The weight causes the rotation to appear to have a force that pushes out from the center. But there is no such thing as centrifugal force. There is a centripetal force that pulls the object toward the center. In a Ferris Wheel, the normal stays parallel and opposite to the weight because the seats rotate with the wheel. In the case of a stationary ball that is connected to a rod, the normal force will point in the same direction as the centripetal force.
Thanks for this! appreciate your work. Just had one doubt. Would the magnitude of g be -9.8 or +9.8? According to me, it should be +9.8 as our reference states that the downward direction is positive.
+Arpit H. Usually down is taken as negative. But you get to choose, just be consistent. You can see a listing of all my videos at my website, www.stepbystepscience.com
+Brian Swarthout But you made the acceleration positive when downwards (at the top), does that mean g would be just 9.8 as its going in the 'positive' direction?
@@rocketjester3337 To be precise, "g" is just the magnitude of the acceleration due to gravity which is always positive. We gave this magnitude its own constant because it is very important to us. "ay", which is the acceleration in the y- direction or in free fall is -g. But I know what you mean. When dealing with centripetal force we typically say that forces that go towards the center of the circle are positive and forces that go outside are negative. You can change it the other way around, making inside negative and outside positive but you would have more negative signs and it would get messier. Remember that the direction of forces is subjective and you can choose the coordinate plane you want. You can do it as you say making centripetal acc. negative at the top and positive at the bottom, and the other forces as you normally treat them, Force normal up and force of gravity down. You will get the same result. I think people use the same sign for centripetal acceleration in their equations in order to show the circular motion that is constantly changing direction. I hope this helps even though I was 2 years late. You're probably a quantum physicist by now.
Well. There are other parts of this problem that can get a little more difficult. For example, the inertia created by the person and point mass. The torque. The angular momentum. Is this an elastic problem? Etc.
