Quantcast

Got Homework?

Connect with other students for help. It's a free community.

  • across
    MIT Grad Student
    Online now
  • laura*
    Helped 1,000 students
    Online now
  • Hero
    College Math Guru
    Online now

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

NotTim Group Title

Determine the magnitude of the apparent weight of a 56 kg student standing in an elevator when the elevator is experiencing an acceleration of (a) 3.2 m/s^2 downward and (b) 3.2 m/s^2 upward.

  • one year ago
  • one year ago

  • This Question is Closed
  1. bahrom7893 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    W = m*a When it's going up, acceleration is: g+a, when it's going down acceleration is g-a

    • one year ago
  2. bahrom7893 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    a) total a = -9.8-3.2 = -13 W = 56*(-13)N

    • one year ago
  3. NotTim Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    You see, here's what I did for a and b.

    • one year ago
  4. bahrom7893 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    b) total a = -9.8 + 3.2 = -6.6 W = 56*(-6.6)N

    • one year ago
  5. NotTim Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    a) f=ma =(56)(3.2+9.81) =728.56N

    • one year ago
  6. NotTim Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    Why is the force negative in both cases?

    • one year ago
  7. bahrom7893 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    because weight is pushing down.

    • one year ago
  8. NotTim Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    Ok. Give me a second to redo this...

    • one year ago
  9. bahrom7893 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    same thing, just change the signs

    • one year ago
  10. bahrom7893 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    you found the normal force, which has the same magnitude, but opposite direction

    • one year ago
  11. NotTim Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    And its alright if my signs are negative? Because the answers are A) 3.7*10^2N and b) 7.3*10^2N

    • one year ago
  12. bahrom7893 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    ohh yea they asked for magnitude. If they just asked for weight, ur answers wld be negative

    • one year ago
  13. bahrom7893 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    since weight has magnitude and direction. In this case it's going down, hence the negative.

    • one year ago
  14. NotTim Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    k. ill work with this. if i need help, ill call out

    • one year ago
  15. NotTim Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    Hey @bahrom7893 ?

    • one year ago
  16. bahrom7893 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    hey

    • one year ago
  17. NotTim Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    the answer for A) was wrong. you probably explained this, but i forgot

    • one year ago
  18. NotTim Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    We got -728.56N. The book says 3.7*10^2N

    • one year ago
  19. bahrom7893 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    Wait in the answer, is the answer for a greater than the answer for b?

    • one year ago
  20. NotTim Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    No.

    • one year ago
  21. bahrom7893 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    A) 3.7*10^2N and b) 7.3*10^2N Aren't those the answers?

    • one year ago
  22. NotTim Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    yup

    • one year ago
  23. bahrom7893 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    oh yea.. obv. Hang on I know what we did wrong

    • one year ago
  24. NotTim Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    for A), i did this: "56)(-3.2-9.81)

    • one year ago
  25. bahrom7893 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    well it makes sense.. i just always confuse the signs of g. g has to be positive in this case.

    • one year ago
  26. NotTim Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    would that make my value of 3.2N positive too?

    • one year ago
  27. bahrom7893 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    http://www.intuitor.com/student/elevatorrProblem.php

    • one year ago
  28. bahrom7893 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    it's the sign of g, i always get confused with it..

    • one year ago
  29. NotTim Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    am I to consider 3.2N a positive or negative force?

    • one year ago
  30. bahrom7893 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    well is it pushing down or up?

    • one year ago
  31. NotTim Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    It's pushing down

    • one year ago
  32. NotTim Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    If it was -ve, it would make sense mathematically, but not in terms of real world physics(for me)

    • one year ago
  33. bahrom7893 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    then it's negative, but they're just asking for magnitude, or abs value of that force.

    • one year ago
  34. NotTim Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    ok. give me a moment to readi guess

    • one year ago
    • Attachments:

See more questions >>>

Your question is ready. Sign up for free to start getting answers.

spraguer (Moderator)
5 → View Detailed Profile

is replying to Can someone tell me what button the professor is hitting...

23

  • Teamwork 19 Teammate
  • Problem Solving 19 Hero
  • You have blocked this person.
  • ✔ You're a fan Checking fan status...

Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.

This is the testimonial you wrote.
You haven't written a testimonial for Owlfred.