A car's brakes must do work in order to slow down a car. In which of the following instances are the brakes doing the most amount of work?
1. Not enough information is given.
2. Slowing down from 70 km/hr to rest
3. Slowing down from 100 km/hr to 70 km/hr
4. Both require the same work.
5. None of these
6. Slowing down from 200 km/hr to 180 km/hr
