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On this page I put together a collection of friction problems to help you understand the concept of friction better. The required equations and background reading to solve these problems are given on the friction page and the equilibrium page .
We usually split the contact force into two components, a normal force perpendicular to the surfaces in contact, and a force of friction that is parallel to the surfaces in contact. It can be useful to look at the whole vector, however. Figure 3.15: Free-body diagrams for the two boxes of Example 3.6.
Three kinds of friction: • Static friction: acts to prevent motion, so points opposite to the direction the object would move in the absence of friction • Kinetic friction: appears when an object slides across a surface; points opposite to the direction of motion • Rolling friction: one surface rolling over another KJF §4.3, 5.5 3
Typical car tires rotate over the surface of the road without slipping, thus the coefficient of static friction determines a car's maximum acceleration in most situations. To solve this problem, set the frictional force on level ground equal to the net force of the second law of motion.
This document contains solutions to 3 physics problems involving static and kinetic friction. The first problem determines the maximum static friction and minimum force needed to start moving an object at rest.
Friction Problems For the following problems, calculate the force of friction acting on the object. 1. A 10 kg rubber block sliding on a concrete floor (µ=0.65) @ ⁄ A 2. A 8 kg wooden box sliding on a leather covered desk. (µ=0.40) @ ⁄ A 3. A 37 kg wooden crate sliding across a wood floor. (µ=0.20) @ ⁄ A 4.
In ALL of these practice problems, you should make the following simplifying assumptions. The masses of all strings are so small compared to other masses that they can be ignored (we can pretend that the strings are massless).
