Acar traveling at 20 m/s when the driver sees a child standing in the road. he takes 0.80 s to react, then steps on the brakes and slows at 7.0 m/s2. how far does the car go before it stops?

When driver see the child standing on road his speed is 20 m/s

So here at that instant his reaction time is 0.80 s

He will cover a total distance given by product of speed and time

now after this he will apply brakes with acceleration a = 7 m/s^2

so the distance covered before it stop is given by

so the total distance covered by it

so it will cover a total distance of 44.6 m

a lot of it means it can be "burned" for energy and sold at one price. if it is scarce, the price will go up