Define non-conservative force and use energy principles to calculate the speed of a crate at point C.

5.1 Define a non-conservative force.

A non-conservative force is a force for which the work done on an object depends on the path taken by the object. Examples include friction and air resistance.

5.2 Use ENERGY PRINCIPLES to calculate the speed of the crate when it reaches point C.

Step 1: Apply the Work-Energy Theorem.
The Work-Energy Theorem states that the net work done on an object equals its change in kinetic energy:

$$W_{net} = \Delta K$$

The net work is the sum of the work done by the tension force ($W_T$), the frictional force ($W_f$), and the gravitational force ($W_g$).

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