For the pendulum system studied in Section 48 Example 8 the

For the pendulum system studied in Section 4.8, Example 8, the force is given by (cf. Figure 4.18, page 210) F = -lmg sin theta = -partial differential/partial differential theta(-lmg cos theta) = -partial differential/partial differential theta V(theta)

Solution

The force is given by,

F = -l*m*g*(sin ) and nothing else is given in this question.

And also this can not be the correct equation because F is representing here the force but the expressions at right hand side is of Energy (or more specifically potential energy), i.e.

F = Kg.m.s^-2

E = Kg.m².s^-2