5 Examples of Solving Centripetal Force Problems - IB Physics

[@yogicentralyt]

I have a test on this unit in 2 days and this helped me a lot, you're the best! TYSM

[@ummiatiqah06]

please do videos for topic 9-12 too!! 🥺 I love your videos I hope they can help me for my May2021 exam 🥺🥺

[@Dark_light7]

I thought it was me who didn't understand, but now I realize I have a really bad professor.

[@cloudy7817]

this did help a little even though I still basically don't know wtf I'm doing

[@Alexandra-vs2cr]

Excellent video, thank you! Example 2 - turning roads: can someone explain how the angle to the ramp is equal to the top angle of the normal force?

[@tiredgirl3074]

Thank you for such a great video! although I had a question in regards to the hill example no. 4, do we not consider applied force and force of friction? Is it due to us assuming that the car is just standing still on top of the hill?

[@AndyMasley]

Good question! While there may be a force of friction and/or applied force, the net force has to point straight down at the top so any horizontal force would be cancelled out by another horizontal force, so they're not really important to the problem.

[@tiredgirl3074]

@@AndyMasley oh I get it now, that makes sense. thank you so much!

[@TheLeafInTheHidden]

Yeah, you would think we would have a lot of time for this, but no, we learn section 6 and 6.1 in one day, leaving the next day to study and the day after is our quiz day.

[@AndyMasley]

RIP

[@TheLeafInTheHidden]

@@AndyMasley yep he says with ib converstions he makes the test due dates close so that the test is "harder" and will cause most people to get a worser mark than the actual level 7s He doesn't really teach us...

[@AndyMasley]

RIP again brah

[@jamesluc6506]

Just wonder why we don't consider the friction force in the example 2 of the banked curve? I think for the ramp problem, we always consider the friction force. Thank you

[@AndyMasley]

In my example I'm imagining the curve has no friction and the car is pushed to the center entirely by the normal force. A lot of banked curve IB problems don't get more complicated than that so I opted to pretend it was frictionless.

[@treasafrancis3]

0:47 I'm a bit confused on this part. Could you elaborate more on what circular path being perfectly horizontal and vertical mean? Does it mean the object's going back and forth in a line? Also confused on why net force can only be horizontal for one and be horizontal and vertical for another

[@goober09]

did you watch the later examples, they helped me understand!.

[@goober09]

ur de besttttt

[@ranjiniravi6118]

Not constant velocity but constant speed. As the direction of the object continuously changes.

[@AndyMasley]

Yup this is correct. The IB language is weird about this and most problems and the equation booklet write it as tangential velocity rather than speed, so I kept the language even though it's technically incorrect :/

[@eatyourcereal6577]

wait im so confused, how can a normal force be bigger than the force applied downwards onto the surface? And moreover, how can it be in the same direction?? Like mathematically I understand why it needs to be like that but how is that physically possible?? Isn't the normal a force always opposite (equal but opposite in direction) by definition to the force applied perpendicular to the surface and into the surface? Also when the car is on the side of the loop de loop how can there be static friction in the car's direction of movement?? I mean the car is moving in that same axis so the friction must be kinetic, and also if its kinetic it should be in the opposite direction no?

[@akixuu]

Thank you for the amazing video 😊

[@tiredgirl3074]

and also would you mind explaining in that same example why is the Normal force smaller than the force of gravity? I didn't understand that part...:)

[@AndyMasley]

Sure yeah! So the normal force is the force applied by a surface to prevent the object from moving through it. On the hill, the car is close to going so fast that it's launched off the top, so it doesn't require the hill to perfectly balance out its weight because it would be going up a bit before coming back down even if the hill weren't there.

[@tiredgirl3074]

@@AndyMasley Right, so if the normal force was the same magnitude as the force of gravity, then the car would be at its max velocity, like you said in the video. that makes it clearer! thanks a lot again! :)

[@09daphnes2a9]

and why is friction not taken into consideration at the bottom and the highest point of the loop de loop situation?

[@HAB315]

Just a question, in the trough example, there won't be any maximum speed for the car right? since the normal force could just continue to match it as the velocity (and proportionally the centeripal force) increase.

[@09daphnes2a9]

May I know if R is bigger than mg in examples 4 (trough), wouldn't the car just topple over?

[@shirpmin7121]

Thankyou sir really appreciated ❤️

[@priyamkamdar1056]

Hi, at 17:45 in the video, you mentioned that the Normal Force at the top of the circle has to act downwards towards the centre of the circle, adding up with the Gravitational Force to become Fc.. but logically, I didn't understand why the Normal Force would act downwards when the weight of the car is also downwards.. What force is present on the road/track that makes it exert an opposite force Downwards??

[@AndyMasley]

Imagine that you set up a trampoline in your living room, and you jump up very fast and hit your head on the ceiling. When you hit your head, there's no force pushing you up into the ceiling, but the ceiling still reacts and says "nope you're not moving through me" and supplies enough force downward to prevent you from moving through it. This force is the normal force, it points down, and it's created because the surface needs to stop you from moving through it, not because there's some upward force that's carrying you up. With the car example, the car's moving fast enough that if the circle weren't there, it would shoot off into the air instead of moving in a more constricted circle, so the surface also needs to supply some force to keep it in the circle and prevent it from moving through the surface, even though there's no upward force propelling the car. Does that make sense?

[@jalencheng]

@@AndyMasley great explanation, i was searching for it online!

[@lumenphysics8608]

Sir can I know the process of explaining with figures,,,plz tell me

[@ardianabani5570]

There are many questionable explanations here. But let's focus on example 5 for example, when you said that since the car is not slipping down then it must be a vertical force that keeps it from slipping and that has to be equal with the force of gravity applied on that car. So if the car is moving up then force of friction should point down, shouldn't it? Also you are saying that since an object is moving in circular motion and since you do not know other forces than Gravity, Normal force and Friction then one or the other is the cause of circular movement. Very primitive explanation of Physics by mixing up effect for the cause. Normal force is the effect of an object pressing on a surface, NOT THE CAUSE. It's never the cause.

[@AndyMasley]

This is incorrect. Any wheel is immobile on its point of contact with the surface it's on. The reason cars don't fall down hills as they move up is that the part of the wheel making contact with the hill is experiencing static friction with the surface, and the friction points up the hill to prevent the car from sliding down. This is very simple HS level physics, there's no debate about this.

[@AndyMasley]

And yes, if you can list all the forces on an object moving in a circle, by definition those forces must add together to make the centripetal force. Again this is a simple high school level fact that isn't debated.

[@pexotrexo3296]

Señora no tiene algo mejor que hacer? He podido resolver todos los ejercicios de física gracias a este video. Haga sus propios videos para ver qué tan bien explica usted.

[@ardianabani5570]

Sorry, but it seems like you are saying that Friction is the Centripetal force, as if friction causes the movement, BUT in fact, friction is the effect of movement, not the cause of it.

[@AndyMasley]

Friction causes the change in motion. If you have a block sliding across a table, friction is causing it to accelerate in the opposite direction of its motion (slow down). In the same way, friction can be the force that causes an object to accelerate toward its center of motion. This is a basic fact of circular motion, it's the reason why cars are able to turn and are unable to turn on ice.

[@ardianabani5570]

@@AndyMasley ​ As you just said it, Friction can cause change in motion as in the opposite of movement. Friction does not change direction of movement. Change in Momentum however, causes the change in direction, and we may "blame" the friction when we do not know our formulas. As for cars that are able to turn on ice, that's because it is the force in engine that causes the thrust and also the wheel mechanism that causes the change of direction for the tires and these two outside forces make the car turn on ice, while some good winter tires increase the friction so that we need less force to apply to cause that change in direction.

[@ardianabani5570]

@@AndyMasley You forget that cars move up the hill or turn on ice not because of friction but because of the engine, that creates the force that moves the wheels and Friction is as a result of object moving. Hence, another force is present to cause the movement, not friction.

[@AndyMasley]

​@@ardianabani5570 you have a misunderstanding of what forces are and how they apply to cars. It might be helpful to watch a series on force.

[@ardianabani5570]

@@AndyMasley If you say so. Now all of a sudden you realize that there is not as simple as friction force, Normal and gravity force? Good for you