PHYSICS: So, would you ever jump out of a plane? Way too much craziness for me! Thanks, Katie, for diving off the lab station for us!!
How was net vertical force? Great job on the problems, but don’t forget things like terminal velocity and the why! And I still don’t know what’s so funny about a fish in an elevator??
🙂
flickr photo by jeroen_bennink
I can’t believe that a scale changes your weight number when you’re on a elevator!
Ok, I’m still having a couple sign issues. Say a person is standing on a scale in an elevator accelerating downward. Does that mean the person on the scale is accelerating up? Or is he accelerating down at a slower rate than the elevator?
I ask because I’m trying to understand why he appears to weigh less. I’m not always sure which direction of force I should use
Jeremy – Hmm… I think you may be waaaay over thinking this. 🙂 Typically, if the problem refers to the elevator as having a downward acceleration (and you’ve previously assigned down as -), that means it is gaining in m/s/s – getting faster as it descends – same thing it would mean if you were moving up and it had an upward acceleration.
The only time you’ll have a bit of a kink is if they tell you, for example, that the elevator is moving upward (and you’ve previously assigned the upward directions as +) and you have a negative acceleration. That would mean you’re moving upward, but you’re slowing down. Same as the rules we’ve always had with motion – when velocity and acceleration are in the same direction, you’re speeding up. When they are in opposite directions, you are slowing down.
We don’t have Science in the News this week right?