Answer the following question given this paragraph: 

People have known about gravity for thousands of years. After all, they constantly experienced gravity in their daily lives. They knew that things always fall toward the ground. However, it wasn’t until Sir Isaac Newton developed his law of gravity in the late 1600s that people really began to understand gravity. Newton is pictured in Figure below .


Q: What did sir isaac newton's famous law help people understand?


A:
gravity