1. The problem statement, all variables and given/known data The length of a slope is 500 meters and it's height is 10 meters. 60 kg sled went down the slope. Find the average friction force if it's speed in the end = 8 m/s (the starting speed = 0) 2. Relevant equations Ft=mv-mv0 t=S/v 3. The attempt at a solution Ft=mv-mv0=60*8=480 Average speed = (8+0)/2=4 t=500/4=125 F=480/125=3.84 N Weight=mg=600 600-friction=3.84 friction=596.16 N Is it correct?