Undergrad Car acceleration if resistance forces don't exist

[Jurgen M]

You showed a 50 N weight on a string pulling a cart. That is a constant force device. It is not a constant power device.

No this not string pulling cart.
Engine/gearbox stay at place and winding wheel lift up weight with rope like cran that has I.C. engine for lifting.Weight is accelerate up.

 

[jbriggs444]

No this not string pulling cart.
Engine/gearbox stay at place and winding wheel lift up weight with rope like cran that has I.C. engine for lifting.Weight is accelerate up.

If you have constant 50 N force, it is a constant force device. Period. End Of Story.

Maybe if it was a 5 kg mass, it could be constant power. But it's not 5 kg. It's labeled as 50 N.

 

[Jurgen M]

If you have constant 50 N force, it is a constant force device. Period. End Of Story.

Maybe if it was a 5 kg mass, it could be constant power. But it's not 5 kg. It's labeled as 50 N.

It has mass of 5kg, on the Earth this aprox 50N, and when accelerate up tension in rope is bigger then 50N...

 

[Jurgen M]

I suspect that he doesn't ride a bicycle!

Indeed bike can travel very fast if reduce aero drag, 183mph (295km/h) !

 

[bhobba]

A car can't have ANY acceleration if there is no resistance anywhere including the tire/road resistance because the wheels would just spin and the car would go nowhere.

What was it Meatloaf said - you took the words right out of my mouth (the rest doesn't apply here ). Seriously the only reason a car can move is the resistance between the tyres and the road. If there is none all the wheels would do is spin - as you mentioned. I seem to recall Feynman discussing it somewhere in his lectures, which of course anyone interested in applied math/physics should read (but not after a usual course in physics without going into why).

Thanks
Bill

 

[bhobba]

Problem is that some members at stackechange who comment at special relativity tags, has different comment,answers then here, so it makes even more confusion for me.

With my mentor's hat on first, this is a thread about classical Newtonian mechanics; relativistic considerations are not appropriate. But different answers to the same question can be confusing; so just a passing comment that there are different approaches to relativity that can lead to different ways of explaining things. I think these days the explanation based on the symmetries of an inertial frame gets to the heart of the matter best:
http://www2.physics.umd.edu/~yakovenk/teaching/Lorentz.pdf

If you would like to discuss the matter further please start a thread in the relativity forum.

Thanks
Bill