This is a simulation of a projectile launched at an initial speed, vo, an
initial angle, th0, and an initial height, yo. The equations of motion are
such that vx=dx/dt, vy=dy/dt, ax=Fx/m, ay=Fy/m. Here the Force is a vector
of the form Fy=-mg-b*vy, and Fx=-b*vx, where b is a coefficient of
friction (air resistance). The user has the capability to change, vo,
thetha, yo,xo, g, m, b, and dt to investigate various effects due to such
changes. Here dt is the step size used in the numerical solution process.
The method being used is the Runge Kutta solver. Making dt smaller slows
the simulation dowm but is more accurate. Increasing dt makes the
calculation run faster at the expense of accuracy. The buttons play,
pause, step, initialize, clear, and reset are used to start the
simulation, pause it, step it slowly, or clear the screen when there are
too many curves, or to restart the simulation afresh. The trace can be
turn on of off by clicking it to show the path or to take it off.