ASTR 100 Lecture Notes - Lecture 5: Net Force, Scientific Method, Gravitational Constant

• School: Ball State University
• Department: Astronomy
• Course: ASTR 100
• Professor: Dr.Eric Hedin

Document Summary

Body at rest tends to stay at rest. A body in motion remains in motion. Experiments with inclined planes, demonstrated the idea of inertia and the importance of forces (friction) Newton"s laws: a body continues in a state of rest or uniform motion in a straight line unless an outside force acts upon it. Cannot move on a curved path w/o forces acting on it: force - a push or pull, the force referenced is a net force. Astronomers of antiquity did not connect gravity and astronomical motion. Galileo investigated this connection with experiments using projectiles and balls rolling down planks. He put science on a course to determine laws of motion and to develop scientific method. Planets move along curved (elliptical) paths, or orbits. There must be a force at work. (gravity!!) Is a universal force that causes all objects to pull on all other objects everywhere.