How can Simple Harmonic Motion have angular frequency?

*InvalidID*

http://www.youtube.com/watch?feature...h_Lr588#t=167s

He says that the tangential component of the force of gravity is -mgsin(θ), but why is it negative? If the tangential component is in the same direction as the velocity, shouldn't it be positive?

InvalidID	How can Simple Harmonic Motion have angular frequency? http://www.youtube.com/watch?feature...h_Lr588#t=167s He says that the tangential component of the force of gravity is -mgsin(θ), but why is it negative? If the tangential component is in the same direction as the velocity, shouldn't it be positive?