Physics:Newton's Apple（10）
On this episode of Newton's Apple， we shall find answers to three questions: First， why must my pet dog Lucy be vaccinated every year? The reason we vaccinate dogs is to protect them from serious diseases. Second， how does a bicycle rider stay upright? Peggy Knapp is getting the answer. And thrid， I have pet fish， I always wonder how a fish breathe.
- Added：2006
- Country：America
- Duration：30
- Time of update：2011/8/16 10:18:10