Physics problem: pushing a wheel over a step

Рет қаралды 9,020

3 жыл бұрын

How big is the force we need to apply to a wheel to push it over a step? In this video I explain my approach to solving this Physics problem.
About me: I studied Physics at the University of Cambridge, then stayed on to get a PhD in Astronomy. During my PhD, I also spent four years teaching Physics undergraduates at the university.
My website: benyelverton.com
#physics #maths #mechanics #statics #forces #resolving #equilibrium

Пікірлер: 22

@YohannesAssefa-wk5oo 8 ай бұрын

i know this question from "ordinary level physics" .And it took me 2 weeks to solve when i was grade 10 after learning about torque. Because there was no internet back then to get answer quickly

@somroy4691 2 жыл бұрын

it was hard for me to understand it with torque . Your video really helped me understand it with simple forces .

@DrBenYelverton 2 жыл бұрын

I'm glad this was helpful! I like the force approach too.

@martaviola6890 3 жыл бұрын

This is actually so smart

@pasindutisuran7648 2 жыл бұрын

How can we find friction?

@brunopereira2475 Жыл бұрын

what happens if the force - contact point between the ball and the force - is not in the center but a bit above?

@DrBenYelverton Жыл бұрын

Good question, I haven't worked through all the details but you should be able to apply the same method as in the video to investigate this. If the force F is coming from something pushing on the wheel, it's a normal contact force and therefore always points towards the centre of the wheel. If you apply it above the centre, it will therefore acquire a downward component, so intuitively I'd expect a larger force to be required.

@sayanjitb 2 жыл бұрын

I solved it by taking torque about the point of contact at the height h.

@DrBenYelverton 2 жыл бұрын

That's a good approach too, that way we don't need to worry about the reaction force at the step.

@TheSunshineRequiem 4 ай бұрын

what happens if it’s a bump instead of a step and the wheel never leaves the ground, normal force would be varying as it climbs up?

@DrBenYelverton 4 ай бұрын

It would indeed!

@user-hi5yz7vs5m Ай бұрын

What happens if F is larger than the calculated value in the video?

@DrBenYelverton Ай бұрын

The force calculated in the video is just the minimum required force for the wheel to climb the step. If F is larger, it will just make it to the top more quickly!

@mohammaddanishsiddiqui6008 6 ай бұрын

I have this doubt that what u did here is that u made the ball loose the contact with ground, but u haven't checked that if the force is enough to make the wheel climb over the step?? I felt like there's a need to conserve energy bw the points when ball is on ground and climbs up

@DrBenYelverton 6 ай бұрын

As soon as the wheel starts moving, the direction of the force S starts to turn towards the vertical, because S always points towards the centre of the wheel. That means its horizontal component is always decreasing. So if F is large enough to set the wheel in motion, and continues to act subsequently, there is a net horizontal force to the right and the wheel will make it up to the top.

@ProdigyNa996 Жыл бұрын

But you can't Count N at equilibrium

@kalashjain3827 Жыл бұрын

Is it possible to solve this by IAOR

@DrBenYelverton Жыл бұрын

Once the wheel starts moving, the centre of rotation will be the point of contact between the wheel and the step - you could approach the problem by taking moments about that point.

@kalashjain3827 Жыл бұрын

@@DrBenYelverton thank you sir