Begin with some exploration of what you can do with the applet and what it shows.
Double the tangential speed (hereafter simply called speed). Don't forget to Initialize.
...How do the velocity and acceleration vectors change?
...How do the force vectors change?
...Do these changes make sense?
Note that the Fric-O-Meter goes off scale. This means that there's not enough static friction to hold the object on the curve. (OK, we know the object keeps right on going. We haven't programmed a skid into the problem yet.)
Restore the speed to its original value and Initialize.
...Double the mass.
...Do the changes or absence of them make sense?
Restore the mass to 5 kg and change the gravitational field strength to the value on Jupiter (25 N/kg). Initialize.
...Note that the velocity and acceleration vectors didn't change. Why not?
...Note that the friction force switched directions. What does that mean?
Restore the gravitational field strength to the Earth value. Initialize.
...Click on the Speed Punch to increment the speed by 1 m/s. Why did the friction force increase?
...Punch the speed again. This gets you into the caution zone.
...If you want to live on the edge, ...
...change the speed increment to, say, 0.1 m/s, and find the speed at which the object skids.
Change the speed increment to -1 m/s and punch it down.
...Note between what speeds the friction force changes direction.
...What happens to the Fric-O-Meter reading when the friction changes direction?
...Make the speed increment smaller so that you can find the speed for which the friction force is zero.
...What you've found is the speed at which the object remains on the curve without friction. This is called the design speed of the curve.
Punch the speed down until you find the point at which the Fric-O-Meter once again exceeds 1.
...What should happen to the object at this point? (Again, the correct object motion won't show on the track, because that hasn't been programmed yet.)
Set the speed to 0. At this point, the object would slide down the track.
...Change the angle to find the value at which the object is stationary but poised to slide.
...Change the angle back to 30°. Now find the friction coefficient for which the object is poised to slide.