ANL - Introduction to Applications of Newton's Laws of Motion

Applications of Newton's Laws of Motion Overview

Introduction

Now that we have a sense of how to use Newton's Laws in isolated instances, it is time to apply these laws to more diverse physical settings where multiple forces from varying origins interact. To aid in condensing the physical setting into mathematical expressions, the free body diagram will be used extensively. Initially, one object will be modeled, allowing an accurate prediction of translational acceleration. Then multiple connect objects will be modeled allowing predication of not only translational acceleration, but also forces internal to the system. We will finish this unit with the analysis of an extremely important class of problems, those involving circular motion.

Essential Questions

1. 1. 1. What are six classifications of forces used to model problems in Newtonian mechanics?
      2. Why is the rotation of an object neglected when applying Newton's laws to translation?
      3. What is the origin of the frictional force?
      4. The coefficient of friction is a measure of what concept?
      5. What are the units of the coefficient of friction?
      6. What is the difference between static and kinetic coefficients of friction?
      7. What is a restoring force?
      8. What is the spring constant and what are its units?
      9. How does one find the acceleration and internal forces of a system of objects that are connected together?
      10. What does the word centripetal mean?
      11. In mathematical terms, what does it mean to not be in contact with a surface
      12. What is the law of universal gravitation?
      13. What characteristic of matter causes a gravitational field?
      14. Why does the gravitational field between two books on a table not cause them to slide together?

Key Terms

1. friction - The force resisting the relative motion of surfaces for solids, proportional to, perpendicular to the normal force and in a direction opposite the motion.
2. Hooke's law - For linear elasticity, a mathematical statement that the force exerted by an elastic object (spring for example) is directly proportional to the displacement, but in the opposite direction F=-kx, where k is the spring constant.
3. inverse square law - any physical law stating that a specified physical quantity is inversely proportional to the square of the distance from the source of that physical quantity.
4. kinetic coefficient of friction - a dimensionless quantity, {Greek letter mu, } k, that relates that relates the frictional force to the normal force for an object in motion.
5. law of universal gravitation - the law which states that every point mass in the universe attracts every other point mass with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.
6. normal force - The force, perpendicular to a surface, exerted on an object by the surface.
7. restoring force - The force exerted by a stretched or compressed elastic object, such as a spring, that tends to return the elastic object to its relaxed (equilibrium) position.
8. spring constant - A constant, k, that relates restoring force to displacement in Hooke\'s law (units are N/m).'
9. static coefficient of friction - A dimensionless quantity, {Greek letter mu, } s, that relates the frictional force to the normal force for a stationary object.
10. tension - The force exerted by inelastic strings, ropes or rods on an object.
11. universal gravitation constant - a physical constant of proportionality between force and the ratio of the product of two masses to the square of the distance between the mass centers square (in the law of universal gravitation).
12. weight - The force on an object due to gravity.

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