15 Forces at Play

Forces at Play by LISA BENJAMIN

丽莎·本杰明著

Do you like to play sports? Sports are fun. They are also work. In science, work is anything that needs force. A force is a push or a pull. It makes something move.

你喜欢运动吗? 运动很有趣。他们也是工作。 在科学中，功是任何需要力的东西。 力是推或拉。 它使物体移动。

A pitcher uses force to throw the ball. He pushes the ball with his hand. The ball moves. Force helps you hit a baseball. The batter pushes the ball with her bat. The ball moves.

投手用力投球。 他用手推球。 球在移动。力帮助你打棒球。 击球手用球棒击球。 球在移动。

Forces stop things from moving, too. This player pulls the ball from the air. The ball stops moving. What happens if the player does not catch the ball? It falls to the ground. Gravity pulls things to Earth.

力也阻止物体移动。 这个球员从空中把球拉下来。 球停止运动。如果球员没有接球会发生什么? 它掉到地上。重力将物体拉向地球。