Restoring force on the bob of a simple pendulum of mass 100 g when its amplitude is 1° is (here acceleration due to gravity =10ms-2)

Restoring force on simple pendulum=  FR=mgsinθ here θ is very small, hence sinθ≃θ ⇒ FR=mgθ            =100×10-3×10×1∘,here 1∘=π180,substitute            =10001000×π180  ⇒ FR=3.14180=0.017 N