it’s moving day for Keanu's family. A small dresser is strapped onto a rolling dolly, and Keanu is supposed to push the dresser out to the moving truck. Keanu is annoyed that they have to help, so instead they throw a 300-gram rubber ball at the dresser. The ball is thrown with a speed of 15 m/s and bounces straight back with a speed of 10 m/s. Unfortunately, this only results in the dresser rolling at a paltry speed of 0.21 m/s, and Keanu eventually decides to just push the dresser anyway. What is the mass of the dresser and dolly combo?