Work done on brakes vs kinetic energy lost by vehicle

[mrjontyy]

When doing work on the brakes of a car or bicycle, how much of that energy is actually removed from the total kinetic energy of the vehicle?
What is the most efficient braking system?

 

[berkeman]

Welcome to the PF.

When doing work on the brakes of a car or bicycle, how much of that energy is actually removed from the total kinetic energy of the vehicle?

Yes, the kinetic energy is being converted into heat in the brake components.

What is the most efficient braking system?

Regenerative braking.

 

[CWatters]

When doing work on the brakes of a car or bicycle, how much of that energy is actually removed from the total kinetic energy of the vehicle?
What is the most efficient braking system?

All of the energy dissipated in the brakes comes from the kinetic energy of the car. ( Unless you are going down hill at constant velocity for example).

You need to define what you mean by "efficiency" in this context. Beckman has given you a good answer based on one definition.