A girl and her bicycle have a total mass of 40 kg. At the top of the hill her speed is 5.0 m/s. The hill is 10 m high and 100 m long. If the force of friction as she rides down the hill is 20 N, what is her speed at the bottom?
【简答题】Many thanks for your offer dated December 26th for leather shoes and for the illustrated catalogues you very kindly sent us. We appreciate the high quality of your goods, but unfortunately we are not ...