Oil, grease and dry lubricants
Answer:
https://www.khanacademy.org/science/physics/work-and-energy/work-and-energy-tutorial/a/what-is-conservation-of-energy
Explanation:
Look at this website it gives you all the details! :)
Answer:
Their velocity is 0m/s because the first box was only 10 kg and the second box was double the weight