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May 5, 2016

# Homework Help: physics

Posted by Jamie Lynn on Wednesday, December 17, 2008 at 5:17pm.

A weight is hung by a cord from the ceiling of an elevator. From the following conditions, choose the one in which the tension of the cord would be the greatest...least?(draw force diagrams)

a) elevator descending at a decreasing spped
b)elevator at rest
c)elevator rising at constant speed
d)elevator descending at increasing speed.

can anyone please explain how to draw these... thanks for your time
• physics - bobpursley, Wednesday, December 17, 2008 at 6:01pm

you have mg downward, and a force at the ceiling pulling upward.
Now, when going upward, there is a force = ma that accelerates the mass upward (if it is accelerating).
Total tension = ma + mg if falling (accelerating downward, a is negative.
If it is at constant speed, then a=0

• physics - Jamie Lynn, Wednesday, December 17, 2008 at 6:03pm

what does mg stand for?

• physics - Jamie Lynn, Wednesday, December 17, 2008 at 6:05pm