Ball shot horizontally, one dropped vertically; both hit the ground at the same time.

What it shows:

The horizontal and vertical motions of a projectile are independent of each other. So two objects falling under the influence of gravity from the same height will reach the ground simultaneously, regardless of their horizontal velocities.

Ball drops from mast of PASCO cart; its motion can be considered relative to the moving cart or the track frame of reference.

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Glider acceleration by an inclined air track or by a falling weight/string attachment; large ballbearing rolling on PASCO track (with strings).

Time lapse image of a ping pong ball rolling down an inclined track. The...

The difference between static and kinetic friction can cause the car to skid when braking.