Classical mechanicsLesson 2 of 3 in the course Newton's Laws of Motion

Common Forces and Fictitious Forces in Newtonian Mechanics

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

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Summary

This lesson explores how surfaces support objects and how gravity can be analyzed on a slope. These ideas help explain why an object can remain at rest on a table or accelerate down an incline.

A surface in contact with an object pushes on it. When this supporting force acts perpendicular to the surface, it is called the normal force, represented by NN. The word normal means perpendicular.

All flashcards

Normal force
A contact force that a surface exerts perpendicular to itself.
Tension
A pulling force transmitted along a stretched flexible connector.
Static friction
A contact force that opposes relative motion or its tendency between surfaces.
Hooke's law
For an ideal spring, its restoring force is F=−kxF=-kx, where xx is displacement from the relaxed position.
Fictitious force
An apparent force introduced when motion is analyzed from an accelerating or rotating frame.

Quiz questions

  1. A stationary load of mass mm is supported symmetrically by two cable segments, each at angle θ\theta above the horizontal. What vertical-force equation determines the tension TT in each segment?Answer: 2Tsin⁡θ=mg2T\sin\theta=mg
  2. A hanging object accelerates upward with upward chosen as positive. Which equation applies to its vertical forces?Answer: T−mg=maT-mg=ma
  3. An ideal spring is displaced by xx from its relaxed position. Which expression gives the spring force?Answer: F=−kxF=-kx
  4. In which frame can an apparent fictitious force arise?Answer: An accelerating or rotating frame of reference.
  5. How does a flexible connector exert force on an attached object?Answer: It pulls along its length, away from the object.

Based on University Physics Volume 1 by William Moebs, Samuel J. Ling, Jeff Sanny (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.

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