1. A pulley system has efficiency 60%. Calculate mechanical advantage to make its velocity ratio 6 .How much amount of effort is required to lift 3000 N load by using this pulley system?​

Mary starts from her house, walks 80 meters south, and stops to chat with her aunt on the sidewalk. after chatting for a few minutes, she walks 125 meters to the west to meet a friend and then walks 45 meters north with her friend to a cafe for lunch. overall, she takes 10 minutes to do all this. what is mary’s average speed?