ASVAB Mechanical Comprehension Practice Test 164952

Questions 5
Topics Coefficient of Friction, Inclined Plane, Joules, Kinetic vs. Static Friction, Net Force

Study Guide

Coefficient of Friction

Coefficient of friction (μ) represents how much two materials resist sliding across each other. Smooth surfaces like ice have low coefficients of friction while rough surfaces like concrete have high μ.

Inclined Plane

An inclined plane is a simple machine that reduces the force needed to raise an object to a certain height. Work equals force x distance and, by increasing the distance that the object travels, an inclined plane reduces the force necessary to raise it to a particular height. In this case, the mechanical advantage is to make the task easier. An example of an inclined plane is a ramp.

Joules

The Joule (J) is the standard unit of energy and has the unit \({kg \times m^2} \over s^2\).

Kinetic vs. Static Friction

For any given surface, the coefficient of static friction is higher than the coefficient of kinetic friction. More force is required to initally get an object moving than is required to keep it moving. Additionally, static friction only arises in response to an attempt to move an object (overcome the normal force between it and the surface).

Net Force

In mechanics, multiple forces are often acting on a particular object and, taken together, produce the net force acting on that object. Like force, net force is a vector quantity in that it has magnitude and direction.