Chapter 6, Problem 7Q

List some everyday forces that are not conservative, and explain why they aren't.

To determine

List some everyday forces that are not conservative and explain why they aren't.

Answer to Problem 7Q

Solution:

The force of kinetic friction$\left({\stackrel{r}{F}}_f\right)$, the tension of a rope$\left(\stackrel{r}{T}\right)$ and the drag force$\left({\stackrel{r}{F}}_D\right)$ are examples of non-conservative forces.

Explanation of Solution

A non-conservative force is one in which the work carried out depends on the trajectory followed by the object. Some non-conservative forces are:

• Drag Force$\left({\stackrel{r}{F}}_D\right)$: This force is commonly associated with the resistance offered by objects when moving in a fluid. The work done by the fluid when an object is dropped on a viscous fluid is different from the work done by the same fluid if the object is pushed into a fluid in a horizontal direction.

• Kinetic Friction Force$\left({\stackrel{r}{F}}_f\right)$: Appears when an object slides on a rough surface, this is opposed to the advance of the object. If a box is pushed on a rough surface by a straight path, the work done is different if that same box is pushed on a curvilinear path.

• The tension of a rope$\stackrel{\perp }{T}$. The work done by a person who pulls a box on an inclined plane is different from the work done if you pull the same box vertically upwards.