Re: [Phys-l] check your work (and kinetic energy)

[brian whatcott <betwys1@sbcglobal.net>]

On 1/7/2012 9:08 PM, curtis osterhoudt wrote:
> Presumably, the same "extra-system object" that did work on the car to accelerate it in the first place (i.e. the ground) is doing the work on the object to slow it down. I must admit I thought about it for more than a femtosecond, but how is the ground NOT doing work on the car to slow it down if the brakes are applied?
I'm probably missing something when I say:  when the car moves right, 
the Earth necessarily moves left.     Later, with the brakes applied, 
the car slows to a halt, the Earth moves to the right, and warm air from 
the disks wafts into the breeze.

Brian W