描述
Pulleys are simple machines used to lift and move loads. Builders use pulley systems to lift tools or materials up high and elevators go up and down with the help of pulleys. Kids will learn how pulleys make work easier and how they are often part of complex machines.
书籍详情
格式
电子书
页数
25 页
语言
英语
已发布
8月 1, 2009
出版商
Bellwether Media
版本
2 个版本
ISBN-10
1612115047
ISBN-13
9781612115047