What is the difference between static and kinetic friction forces?

Question

BlackTom AI · Accepted Answer

To understand the difference between static and kinetic friction, we examine what each type responds to in real motion scenarios.
Option a: 'Static friction acts when the object is moving vertically, kinetic friction acts when the object is moving horizontally.' This mixes directions with friction type; friction is not defined by vertical vs horizontal motion, but by whether the contact is stationary or sliding.
Option b: 'Static friction acts when the object is at rest, kinetic friction acts when the object is moving.' This aligns with the standard definitions: static friction prevents motion up to a maximum value when there is no relative motion at the contact, while kinetic (sliding) friction acts when there is ongoing relative motion between surfaces.
Option c: 'Static friction acts when the speed is constant, kinetic friction acts when the object is speeding.' Speed being constant does not distinguish static friction; even with constant speed, the contact could be at rest or sliding relative to the surface, so this phrasing is misleading and incorrect.
Option d: 'Static friction acts when the object is moving, kinetic friction acts when the object is at rest.' This reverses the actual roles: static friction resists the onset of motion (when at rest relative to the surface), whereas kinetic friction acts during ongoing motion, not at rest.
In sum, the core distinction revolves around whether the contact points are stationary relative to each other (static) or in continuous sliding (kinetic). The options attempt to assign friction types to various motion scenarios, but only one captures the conventional definitions accurately, while the others mix up the conditions or introduce irrelevant criteria such as direction or speed constantness.

UCIC 202503 PHYS101 Quiz 2

What is the difference between static and kinetic friction forces?

查看解析

登录即可查看完整答案

类似问题

What is a resistive force?

What is the unit of friction force and what is the unit of coefficient of friction?

What is the difference between friction force and coefficient of friction?

What does a coefficient of friction depend on? What does a coefficient of friction not depend on?

What is the cause of friction between an object and its environment?

Why does an object have the friction force and what is the direction of the force?

A block is pushed along a horizontal surface and comes to rest after 4.0 m. Which best explains why it stops even though no force is applied once released?

A box rests on a horizontal rough surface. A small horizontal force is then applied and gradually increased until the box just begins to move. Which of the following statements is TRUE?

更多留学生实用工具

考试浏览器助手

风格化写作助手

论文查重助手

文献引用助手

课堂转译助手

课堂笔记助手

Quiz搜索助手

学校历年真题

智能刷题助手

智能匹配练习

希望你的学习变得更简单