The instantaneous position (black dot), velocity vector (green) and acceleration vector (orange) of an ideal pendulum (approximated as a harmonic oscillator) are shown as a function of the time t. The instantanous (x,y) values, the instantaneous values of the (x,y) components of the velocity and the instantaneous values and vectors of the tangential and normal acceleration can be hidden by de-selecting the "Show *" boxes. The initial angle and length (with null velocity) can be adjusted by clicking and dragging the black dot. The time can be set to a given value, reset to zero or let to evolve using the blue bar and labelled boxes.