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Main » Kinematics & Dynamics » Newton's Laws » Lesson I.6.3

### Newton's Laws of Motion - Lesson I.6.3

 Key Terms: Inertia |Galileo's Thought Experiment |

 Newton's First Law of Motion Sometimes called the "law of inertia". It was based on Galileo's ideas of inertia. Often stated as: At object at rest tends to remain at rest and an object in motion tends to remain in motion ( in a straight line at a constant speed - no acceleration) unless acted upon by an external unbalance or net force. Or Objects keep doing what they were doing unless acted upon by an unbalanced force. Your Turn Try the following experiments and describe how they illustrate Newton' First Law. Stack two pieces of wood on a table. Give the bottom block a sharp horizontal tap with a hammer. Remove the end from an open box. Place a ball in the center of the box. Move the box along the table, keeping the ball in the center, with the open end forward. Suddenly stop. Remove the end from an open box. Place a ball in the center of the box. Move the box along the table, keeping the ball in the center, with the open end facing back. Suddenly accelerate.