The Hashemite University
Faculty of Engineering
Me chanic al Engine ering Departme
nl
Machine Design I
Fall 2009
Instructor: Dr. Ala Hijazi
First Exam
Part IClosed Book
Please Read
Questions
Carefully

GoodLuck!
(12 pointsl
l. For the flowing statements
circle
the conect answer.
Ceramics
arebrittle andmuch stronger
in compression
than
in
tension.
Thermoset
polymers
canbe melted andreformed.
The factor of safety
is dbfined as
the ratio of strength
to stress.
If30 parts
fail out ofeach100 parts,
this means
that
the reliability
is 0.3.
Coldworking
increases
the ductility ofthe material.
For a rotating
ring, the maximum stress
occurs at the outer
surface.
In a thickwalled pressure
vessel
the stress
increases
as we move
away
from the
innersurface.
Stress
concentration
factors should be used
for both brittle and
ductile materials.
During quenching,
a part will be cooled at a very fast rate using
water or oil.
Two sets of data werefound
to have a normal distribution. Data set A has a mean of40
anda standard
deviation of5. while dataset
B has a mean of 42 and a standard
deviation
of 3. which of the
following
is true?
a)
All the data points ofset A arebigger than
those ofset B
b)
All the data points ofset A are smaller than
those ofset B
(Q
The same percentage
of data points
in sets A and B are smaller
than 45
Tt
Half of rhe data ooinrs
in set B are smaller
than 40
e)
None ofthe above
Name:
Student #:
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 Spring '10
 علاءحجازي
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