Whenever I see someone pull the ripcord on tv, from the angle of the jumping cameraman, the parachutist looks like he is going straight up really fast as soon as the chute opens.
Is it an optical illusion because the cameraman is still free-falling, or does the force of the air hitting open chute launch you upwards?
It’s a perspective thing. Consider even if you were on the ground, you would be trackign somethign that suddenly changed momentum DRAMATICALLY. Like, from 120mph in freefall to around 5 or 10mph with the chute. Even if you’re expecting it, compensating for that drastic of a change is nearly impossible, so you see the camera continue to track at the same rate for a short instant while the skydiver in effect, stops dead. On your TV screen, all you have for points of reference is the top and bottom edges of the screen, so the optical illusion makes it look like the diver suddenly shot upward.
A better term would be relative motion. The cameraman is still falling at terminal velocity. The parachutist was travelling at terminal velocity and was thus static with regard to the cameraman, but after pulling the rip cord suddenly decelerates, thus the cameraman shoots past.
Another way of looking at it is two cars racing. To begin with, they’re neck and neck. But one applies the brakes (the parachute) and the other doesn’t. The one that doesn’t goes past the one that does.
To be annoyingly pendantic, they both continue to travel at terminal velocity, but the change in mass to surface area with the parachute open means that your terminal velocity is much slower. Parachutes are, in fact, packed to open over several seconds so that you don’t decelerate too fast; you won’t reverse direction.
When watched from the ground:
Fast little dots falling… falling… falling fast…
Then, fast little dots are still falling and now chute is coming out of them… and now I hear fluttering a moment later… little more fluttering… louder… chute is fully open…
…Fast little dots are just slowly descending people with big parachutes now.
Nothing dramatic… nothing tricky to the eye. They go from fast to really slow in a couple of seconds as the chute opens.
If the chute actually launched you upward, then it would be possible to pull your chute just before hitting the ground. This is not the case.
Heck we wouldn’t even need airplanes 
To add to the pedantry, very few people have an actual ripcord on the main canopy, it’s a “hand deployed pilot chute” (there are two varieties, throw-out and pull-out, which have some minor technical differences). The pilot chute is kept folded in a small pouch (either on the leg pad or the bottom of the container) and it’s got a little handle (hackeysack or a short piece of plastic pipe) attached to the top. You grab the handle and throw the pilot chute out to the side. 120mph air inflates the pilot chute which basically stops and acts as an air anchor. As the skydiver continues falling the the pilot chute & bridle pull a closing pin (opening the container flaps), extracts the deployment bag (the main canopy is kept folded in a small bag with the suspension lines S-folded and attached to the bag with rubber bands), pulls the suspension lines tight and at that point the d-bag begins to come off the canopy which inflates and becomes a wing. As the canopy spreads sideways it forces a piece of fabric called the slider down the suspension lines - the slider is an important part which slows the opening down to a comfortable level.
With the reserve canopy there’s an actual ripcord and the pilot chute is spring-loaded and kept inside the reserve container. When the ripcord is pulled that opens the flaps of the reserve container and the reserve chute literally leaps out (the spring is quite strong, it’s meant to rocket the reserve pilot chute well away from your body and any mess that you happen to be in when you need the thing).
[quote=“Valgard, post:7, topic:509875”]
The pilot chute is kept folded in a small pouch (either on the leg pad or the bottom of the container) and it’s got a little handle (hackeysack or a short piece of plastic pipe) attached to the top.
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I found a troll doll with this :eek: expression, I cut the head off and used that for my pilot chute pud, totally froody