What do sailboats and theater curtains have in common? Your readers will learn the answer; it's pulleys. The pulley plays an important role in modern daily life. This simple machine makes raising and lowering heavy loads much easier. From fixed pulleys to moveable and compound pulley systems, readers gain an
Find out about the technological breakthroughs and brilliant inventions that have shaped the modern world. Investigate the science behind everyday life - from cameras and computers to communication and transportation.