The car passes point A with a speed of (solved)

The car passes point A with a speed of 25 m/s after which its speed is defined by v=(25 - 0.15s) m/s. Determine the magnitude of the car’s acceleration when it reaches point B, where s = 51.5 m and
x = 50 m.
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Book used: R. C. Hibbeler and K. B. Yap, Mechanics for engineers - dynamics. Singapore: Pearson Education, 2013.

[@saujanyapoudel8910]

0:16 can you please explain how x=50 when s=51.5. I tried equating v=dy/dx (dy/dx is also velocity, right?) but making substitution s=51.5 gave me x=-5398.4375 instead

[@bimpliscuit4731]

I would love a video on how to find the normal force for the car at this point

[@QuestionSolutions]

Did you mean normal acceleration or actually the normal force? If it's the latter, it'd just be a force upwards that's perpendicular to the surface the car is on and you can show it at the center of mass. Please kindly take a look at: kzbin.info/www/bejne/e6nMep19nq-Naa8

[@ompabaletserametse8643]

The trick for finding normal is finding the angle of inclination : tan(angle) = dy/dx or 1st derivative . Then you find that normal force = weight × cos(angle)

[@kylalakheeram1405]

Is there a way to find the radius if the x value is not given? The version in the assignment I am working on does not provide x. Thanks for the very helpful video solution!

[@QuestionSolutions]

What is given to you instead of the x-value?

[@kylalakheeram1405]

@@QuestionSolutions it's all the same information as what you show in the video, just without x. There's the same s value, same diagram, etc.

[@TANTIBEN]

Ye same here, same problem but the x value isn't given, daz why I'm here, to check it out the solution

[@fredygarinaworld1158]

thank you

[@QuestionSolutions]

You're welcome!

[@emirhanartik5573]

Hi sir, thank you for solution. However I have a question. What should we need to do if we don't have x coordinate of point B ? Should we use arclength formula to find x or is there any other way to solve question ?

[@QuestionSolutions]

Then yes, you'd have to use the arclength formula. Most of the time, these types of questions will give you the x location, its rare for it to not give it.

[@Khadra2024]

How you integrate the last part of (an) I didn’t get it 💔

[@QuestionSolutions]

What time are you talking about? I don't think we integrated anything in this question 😅

[@ompabaletserametse8643]

I just watched the video in reverse, Sir you did integrate.

[@fatwaomydea3801]

Why the final results is different if i use vt^2-v0^2=2as?

[@fatwaomydea3801]

with va = 25 m/s and vb is 17.28 m/s

[@QuestionSolutions]

I am not sure where you are applying this equation. Are you trying to find tangential acceleration? Can you do a step by step breakdown of how you used that equation? So what values you plugged in to each variable? Then I can see where the answers don't match up. Thanks!

[@fatwaomydea3801]

Yes to search the tangential acc

[@fatwaomydea3801]

But i've tried it, its different tho

[@QuestionSolutions]

@@fatwaomydea3801 I see what happened. You cannot use the equation you are using, that is only if velocity is constant. In this problem, velocity is given with respect to distance traveled, so to get acceleration, we have to use ads = vdv.