Klint and Matt decided to race go-Karts down the hill at their house. The mass of Matt's go-Kart is 86kg. Klint's cart falls apart halfway down the hill. Matt's go-cart makes it all the way to the bottom in 40 seconds. If the total distance of the hill is 80 feet, what is the acceleration of his go-cart?

All we can say from the given information is that Matt's

average speed from the top to the bottom is

(80 feet) / (40 seconds) = 2 feet per second.

We're not told whether his acceleration was constant

all the way down. IF it was, then we could use

Distance = (1/2 acceleration) x (time²).

80 ft = (1/2 acceleration) x (40 sec) ²

Divide each side

by 1600 sec² : 80 ft / 1600 sec² = 1/2 acceleration

Multiply each side

by 2: 160 ft / 1600 sec² = acceleration

Acceleration = 0.1 ft/sec².