Newton's Laws of Motion
After completing this lesson you will be able to:
- Define the following terms: inertia, free body diagram, unbalanced force, net force, inertial mass.
- Explain what inertia means and state that mass is a measure of inertia.
- State Newton's laws of motion and provide various applications of these laws.
- Explain what is meant by an unbalanced force.
- Analyze situations involving forces with the aid of a free body diagram.
- Transfer an understanding of vector addition to applications involving Newton's laws of motion.
- Solve problems involving Newton's laws of motion.
- Predict the direction of acceleration on an object, given the direction of the unbalanced force and vise versa.
- Interpret direct and inverse relationships, as they occur in Newton's second law.
- Demonstrate an understanding of the relationship between the SI unit of force (Newton) and the corresponding fundamental units.
- Explain how the inertial mass of an object can be determined.
- Inertia is the property of an object that resists changes in its state of rest or motion. Mass is a measure of the inertia of an object.
- Newton's first law of motion (Galileo's Principle of Inertia) describes what Galileo had discovered about inertia in his "thought experiments".
- A net force is the resultant of all forces acting on an object. Equilibrium exists if the net force is zero. (There must also be no resultant torque.)
- An unbalanced force exists when the net force does not equal zero.
- If no external unbalanced force acts on an object, its velocity will remain constant (i.e., it will remain at rest it it was initially at rest, or continue moving in a straight line at a constant speed, if it was initially doing so).
- An object at rest on a table has its weight opposed by a normal force acting on the object by the table.
- Many practical applications of Newton's laws are evident in common occurrences.
- Free body diagrams are useful to analyze situations involving more than one force acting on a body. Vector addition can be used to determine the net force.
- When a net force acts on an object, it accelerates in the direction of the net force. (Newton's second law)
- Acceleration is directly proportional to the force for a constant mass and inversely proportional to the mass for a constant force.
- The relationship between the SI unit for force and the corresponding fundamental units can be illustrated from Newton's second law.
- Newton's third law states that for every action force a reaction force exits which is equal in magnitude but opposite in direction. These action-reaction forces act on different objects.
- To solve problems relating to force and motion, geometric methods using vector diagrams, trigonometry, or vector component methods are some different ways to arrive at similar results.
- Architects, engineers, and people involved in a wide variety of other related disciplines require a thorough understanding of Newton's laws of motion.