**SAT 2 Physics Discussion Thread Oct 2016**

@Adityaskumar Oh wait…I get it…the word “Perfectly” threw me off for no reason

@Adityaskumar The question never said anything about using someone inside the plane as a point of reference… to an observer who is not moving (which should be assumed since the question didn’t specify), he has both KE and PE, but much more PE. Because energy is a scalar it shouldn’t matter what direction his velocity is in; he still has KE. At least that’s what I gathered from my searches online.

@gmanhax possibly Wat is the relativity answer tho?

@Adityaskumar

I put that the guy measured his own station as being longer.

@bobthebuilder13 I chose that option too.

that’s exactly what I thought… it was almost purely electricity and some dynamics, but it’s supposed to be like 40% kinematics and there were like 2 kinematics problems

I got longer as well for the relativity question.

There wasn’t much kinematics, but the kinematics questions that showed up near the end were free points. The acceleration for anything in the air is 9.8m/s^2 downward, and you could cross out like 2-3 answer choices knowing that alone for each of those.

@gmanhax Wasn’t it -9.8 m/s^2 ??? In the corner of the diagram shown, there was a teeny tiny axis with y in the up direction positive. So I thought since acceleration is downwards, it should be in the negative y axis… giving -9.8 … Oh noooo… all those questions… D’: I messed it up…

@seyll00

Wait so what was the right acceleration? Negative or positive?

@bobthebuilder13 idk!! I marked -9.8 .

@seyll00

that’s what I marked too. Isn’t that right??

@gmanhax said that it’s 9.8 m/s^2…

If what you said is right, about there being an axis on the picture, then the gravitational acceleration has to be negative.

I’m pretty confident that that was a tiny axis indicating the positive y axis. aww… now I’m all worried though…

This is for sure that it doesn’t matter if it was vertical or horizontal velocity. But the point is that if you say there is more PE than KE how can you justify it without values? May be kinetic energy is greater than PE. You don’t know the height at which the plane is moving. There is no pint of making random guesses on the paper. I think it would be all PE because when the parachutist leave he is at rest with respect to the plane.

@“Muhammad Sheheryar Naveed”

They gave u values. When u calculated, PE was greater than KE.

@bobthebuilder13
Was height given?

@bobthebuilder13 Was height given as well?

Can anybody justify the relativity question was it longer or shorter please justify?

@“Muhammad Sheheryar Naveed”

Yes, the height was given as well. As for the relativity question, the guy on the other space station or whatever observes your length as shorter because of length contraction. That means that he measures his own station as being longer. So the right answer was longer.