Which requires that the brakes of a car do the most amount of work? 1. none of these 2. slowing down from 50 km/h to rest 3. both require the same work 4. slowing down from 100 km/h to 50 km/h 5. not enough information is given

4. Slowing down from 100 km/h to 50 km/h

Step-by-step explanation:

The work done by car is given as the change in the kinetic energy of the car. Mathematically,

W = ΔK

where

W = work done by the brakes.

ΔK = Change in kinetic energy.

Kinetic Energy is given as:

Case 1: The car goes from 50 km/h to 0 km/h

ΔK =

ΔK =  

ΔK = 1250m J

∴ W = 1250m J

Case 2: The car goes from 100 km/h to 50 km/h

ΔK =

ΔK =

ΔK = 5000m - 1250m

ΔK = 3750m J

∴ W = 3750m J

Note: Mass of the car is constant.

Hence, slowing down from 100 km/h to 50 km/h requires the brakes to do more work, precisely 3 times more work

answer: i guess 5 units?

step-by-step explanation: