Elevator and mass of a student help

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Homework Help Overview

The problem involves a student weighing 735 N who steps into an elevator that accelerates upwards. The question seeks to determine the student's mass during this acceleration period, with a focus on understanding the relationship between weight, mass, and acceleration.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants discuss the meaning of weight in Newtons and its conversion to pounds, questioning the implications of the student's weight on the calculation of mass. Some suggest using the formula F=ma to find mass, while others clarify that mass remains constant regardless of the elevator's motion.

Discussion Status

The discussion is active, with participants providing insights into the definitions of weight and mass, and exploring different interpretations of the problem. Some guidance has been offered regarding the use of formulas, but no consensus has been reached on the best approach to the problem.

Contextual Notes

There is a mention of the gravitational constant and its role in calculating mass from weight, as well as the potential confusion surrounding the student's weight in different contexts. The discussion reflects a need for clarity on these concepts without resolving the problem itself.

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1)A student weighing 735 N steps into an elevator and pushes the button to go up. If the elevator accelerates at 3.5 m/s2 for 3.0 s, what is the mass of the student during this time?



2)f=ma, v=d/t



3)i don't quite understand how the student can weigh 735 N and consequently I'm completely lost on this question.
 
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Well, do you know what a Newton is? It's a unit of force, like a pound. Saying that a student weighs 735 N is the same as saying that the student weighs 165 pounds. (One pound is equal to about 4.45 Newtons; this is a value you can look up.)

If it helps you solve this problem, use the weight of 165 pounds to figure out the student's mass. But if you do, you should probably go back and do it again without converting the student's weight into pounds. Get used to Newtons, because as long as you're doing physics, you're going to see them a lot.
 


Was that really the question? If the student weighs 735 N, then use F= mg so m= F/g= 735/9.81 to find the mass. Mass doesn't change if you are on an elevator.

IF the problem said that his weight on the elevator was 735 N, then you could use 735= m(9.81+ 3.5) to find his mass.
 


thank you both of you! :D
 

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