"How to compare the speed of doing work" ppt-Guangdong-Shanghai version nine courseware

Guangdong and Shanghai Version 9 "How to compare the speed of doing work" ppt Thinking 2: Which one does a crane and a person do work faster? why? Do you agree with them? What is your opinion? When comparing the speed of work done by an object, two factors must be considered: one is: how much work the object does W the other is: the time t the object does