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I used this clip when teaching about free-fall and projectile motion. Students forget that at the top of the parabola for a projectile a is still -9.8 m/s/s; the common answer is "0 m/s/s." This clip helped in the discussion of why that "0" isn't correct. and that really it's v that is 0 m/s. If v and a were both 0, then what happened to Peter would take place.