Register to reply

Force Elevator Problem!

by whoopie88
Tags: elevator, force
Share this thread:
whoopie88
#1
Oct13-10, 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!!
Phys.Org News Partner Science news on Phys.org
What lit up the universe?
Sheepdogs use just two simple rules to round up large herds of sheep
Animals first flex their muscles
PhanthomJay
#2
Oct13-10, 10:54 PM
Sci Advisor
HW Helper
PF Gold
PhanthomJay's Avatar
P: 6,038
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 .
whoopie88
#3
Oct13-10, 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?

whoopie88
#4
Oct13-10, 11:09 PM
P: 52
Force Elevator Problem!

I also don't understand how to find (e)..
whoopie88
#5
Oct13-10, 11:28 PM
P: 52
Okay after working on this, I've solved it. Thanks anyways!


Register to reply

Related Discussions
Relationship between normal force and sum of the force in elevator problem.. Advanced Physics Homework 4
Elevator force problem Introductory Physics Homework 1
Elevator Force Introductory Physics Homework 2
Quick elevator force problem Introductory Physics Homework 3
Physics problem: elevator force Introductory Physics Homework 1