
#1
Oct1310, 10:44 PM

P: 52

1. The problem statement, all variables and given/known data
Your mass is 65 kg. You stand on a bathroom scale in an elevator on Earth. (a) What force would the scale exert when the elevator moves up at a constant speed? (b) What force would the scale exert when it slows at 2.1 m/s2 while moving upward? (c) What force would the scale exert when it speeds up at 2.1 m/s2 wile moving downward? (d) What force would the scale exert when it moves downward at a constant speed? (e) What force would the scale exert when it slows to a stop at a constant magnitude of acceleration? 2. Relevant equations f=ma fg=mg fnet=mAnet Ff=μῦFn 3. The attempt at a solution I honestly have no idea what to do with all these Y forces going everywhere..Can someone walk me through the process of solving this problem? THANK YOU IN ADVANCE FOR ANY HELP!! 



#2
Oct1310, 10:54 PM

Sci Advisor
HW Helper
PF Gold
P: 5,963

Draw free body diagrams. There are 2 forces acting on the person, the person's weight, acting down, and the normal (scale) force acting up. Use Newton's laws F_net = ma when accelerating. At constant speeed or at rest, F_net =0 (no acceleration, per newton 1). Please show an attempt .




#3
Oct1310, 11:09 PM

P: 52

I found (a), (c), and (d), but I can't find (b). Here is my attempt at solving it:
mAnet = Fn + Fg mAnet  Fg = Fn 65(2.1)  65(9.81) = Fn 774.15 = Fn Help? 



#4
Oct1310, 11:09 PM

P: 52

Force Elevator Problem!
I also don't understand how to find (e)..




#5
Oct1310, 11:28 PM

P: 52

Okay after working on this, I've solved it. Thanks anyways!



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