- #1
Prashant91
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Homework Statement
A person stands on a scale in a elevator at rest. The scale reads 900N.
1) what is the persons mass
2) the elevator accelerates up at 2.5m/s^2. What does the scale read now ?
3)The elevator then continues to move upwards with a steady speed of 4m/s for 5 seconds. What does the scale read during this period
4)the elevator now decelerates at 1.8m/s^2 until it reaches zero velocity. What does the scale read during this period[/B]
Homework Equations
: F=ma and W=mg [/B]The Attempt at a Solution
1) rearrange w=mg for m = 900/9.81 = 91.7kg
2) a= 9.81+2.5 = 12.31 so f=ma ... f=91.7*12.31 = 1128.8N
3) I AM COMPLETELY STUCK ON THIS PART ? -if it is moving upwards at 4m/s for 5 seconds. Then there would be no acceleration as a=0
so the scale would read the same 1128 N
would i need to show any working out instead of w=mg = 91.7* 9.8 ?
4) COMPLETELY STUCK - I UNDERSTAND A= -1.8M/S^2 as it is decelerating [/B]
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