Force Elevator Problem!

  • Thread starter whoopie88
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  • #1
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Homework Statement


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?

Homework Equations


f=ma
fg=mg
fnet=mAnet
Ff=μῦFn


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!!
 

Answers and Replies

  • #2
PhanthomJay
Science Advisor
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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
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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
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I also don't understand how to find (e)..
 
  • #5
52
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Okay after working on this, I've solved it. Thanks anyways!
 

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