- #1
bksree
- 77
- 2
Hi all
Please clarify this doubt on work done by friction. The text referred is from the book 'Introduction to classical physics by Morin' - Chap 5, sec 5.1
He is referring to the work-energy theorem : Wexternal = ΔK + ΔV + ΔKinternal
"Consider a car that is braking (not skidding). The friction force from the ground on the tires is what causes the car to slow down. But this force does no work on the car, because the ground isn't moving; the force acts over zero distance. So the external work on the left side (of the above equation) is zero. The right side is therefore also zero. That is the total energy of the car doesn't change. ... ΔK = - ΔKinternal ..."
My doubt is regarding the line But this force does no work on the car, because the ground isn't moving; the force acts over zero distance
The frictional force (rolling friction since the car isn't skidding) by the ground ON the car is F = μkN where N = wt of car. This acts opposite to the direction of motion and isn't work done by friction given by ( F*dist traveled during braking)
Please clarify
TIA
Please clarify this doubt on work done by friction. The text referred is from the book 'Introduction to classical physics by Morin' - Chap 5, sec 5.1
He is referring to the work-energy theorem : Wexternal = ΔK + ΔV + ΔKinternal
"Consider a car that is braking (not skidding). The friction force from the ground on the tires is what causes the car to slow down. But this force does no work on the car, because the ground isn't moving; the force acts over zero distance. So the external work on the left side (of the above equation) is zero. The right side is therefore also zero. That is the total energy of the car doesn't change. ... ΔK = - ΔKinternal ..."
My doubt is regarding the line But this force does no work on the car, because the ground isn't moving; the force acts over zero distance
The frictional force (rolling friction since the car isn't skidding) by the ground ON the car is F = μkN where N = wt of car. This acts opposite to the direction of motion and isn't work done by friction given by ( F*dist traveled during braking)
Please clarify
TIA