Solve for Apparent Weight: Newton's Second Law in Elevator Scenarios"

[shawonna23]

A 79.0 kg person stands on a scale in an elevator. What is the apparent weight in each of the following situations?
(a) when the elevator is accelerating upward with an acceleration of 1.80 m/s2
? N

(b) when the elevator is moving upward at a constant speed
? N

(c) when the elevator is accelerating downward with an acceleration of 1.70 m/s2
? N

 

[maverick280857]

1. Draw a freebody diagram for each case.

2. How would you measure apparent weight. How would you write an expression involving the forces shown on a freebody diagram and the apparent weight?

3. Include your reasoning/solution before asking for help

Cheers
Vivek

 

[shawonna23]

Here Is What I Came Up With

A. FN=mg+ma
(79.0*9.8)+(79.0*1.80)=916.4

B. (79.0*9.8)+(79.0*0)=774.2

I still don't know how to get the answer for c

 

[faust9]

Did you draw a new FBD for part c and go through the process of summing the forces again?

 

[maverick280857]

Did you draw a new FBD for part c and go through the process of summing the forces again?

You're this : . : close from solving part (c). Just go ahead and follow faust9's advice and you'll be through (if you could you parts (a) and (b) there's no reason why you can't get (c) since the reasoning is similar...only the forces are to be accounted for correctly).

Cheers
Vivek