PLTW Final Exam Questions with Correct Answers
Precision Correct Answer-Engineers communicate precisely to others
Use clear definitions
State the meaning of variables
Are careful about specifying units
Calculate accurately
Express answers with a degree of precision appropriate for the problem
context
Why is it important to use constraints when sketching with your 3D
modeling program? Correct Answer-Because constraints allow you to
move shapes accordingly in order to best represent the object you are
sketching.
Why are some constraints automatically applied by the software, but you
must manually apply others? Correct Answer-Because some shapes
come with automatic constraints. Squares for instance, have two sets of
parallel sides and all sides are equal in length.
Fillet Correct Answer-A curve formed at the interior intersection
between two or more surfaces.
Explain the difference between weight and mass. Correct Answer-
Weight is the force of gravity acting upon an object, while mass is the
quantity of matter in an object.
,Density Correct Answer-a measure of the amount of matter per unit of
volume
Matter: Mass vs. Weight Correct Answer-Mass is the amount of matter
in an object or the quantity of the inertia of the object.
Weight is the force of gravity on mass.
W = weight
m = mass
g = acceleration of gravity
SI units weight and mass Correct Answer-mass = kilograms and weight
= newtons
Us Customary weight and mass Correct Answer-mass = slugs, more
commonly pound-mass(lb^m) 1 lbm = 0.45359237 kg and weight =
pounds
How are pound-mass and pound-force related? Correct Answer-On
Earth (g = 32.174 ft/s2): 1 pound-mass object weighs 1 pound-force
In outer space (no gravity): 1 pound-mass object has no weight
On the moon (g = 5.32 ft/s2): 1 pound-mass object weighs 0.166 pound-
force
How can density be indicated? Correct Answer-Mass density and weight
density
, Mass/Weight Density Correct Answer-Mass Density commonly used for
SI units
g/cm3 or kg/m3
Weight Density commonly used for U.S. Customary units
lb/in.3 or lb/ft3
Balance—measures mass Correct Answer-Uses objects of known mass
to find the unknown mass of an object
Measurement is unaffected by difference in gravity
Scale—measures weight Correct Answer-Measures force caused by
gravity
Measurement is affected by difference in the acceleration of gravity
May display a "mass" measurement reading by using an assumed
acceleration of gravity to convert from weight to mass
Volume: Measurement Correct Answer-Volume is the amount of three
dimensional space enclosed by an object.
Finding Volume:
Calculate using geometry of object
Measure indirectly using water displacement (or 3D scanner)
Surface area Correct Answer-is the sum of all the areas of the faces of a
three-dimensional solid.
Precision Correct Answer-Engineers communicate precisely to others
Use clear definitions
State the meaning of variables
Are careful about specifying units
Calculate accurately
Express answers with a degree of precision appropriate for the problem
context
Why is it important to use constraints when sketching with your 3D
modeling program? Correct Answer-Because constraints allow you to
move shapes accordingly in order to best represent the object you are
sketching.
Why are some constraints automatically applied by the software, but you
must manually apply others? Correct Answer-Because some shapes
come with automatic constraints. Squares for instance, have two sets of
parallel sides and all sides are equal in length.
Fillet Correct Answer-A curve formed at the interior intersection
between two or more surfaces.
Explain the difference between weight and mass. Correct Answer-
Weight is the force of gravity acting upon an object, while mass is the
quantity of matter in an object.
,Density Correct Answer-a measure of the amount of matter per unit of
volume
Matter: Mass vs. Weight Correct Answer-Mass is the amount of matter
in an object or the quantity of the inertia of the object.
Weight is the force of gravity on mass.
W = weight
m = mass
g = acceleration of gravity
SI units weight and mass Correct Answer-mass = kilograms and weight
= newtons
Us Customary weight and mass Correct Answer-mass = slugs, more
commonly pound-mass(lb^m) 1 lbm = 0.45359237 kg and weight =
pounds
How are pound-mass and pound-force related? Correct Answer-On
Earth (g = 32.174 ft/s2): 1 pound-mass object weighs 1 pound-force
In outer space (no gravity): 1 pound-mass object has no weight
On the moon (g = 5.32 ft/s2): 1 pound-mass object weighs 0.166 pound-
force
How can density be indicated? Correct Answer-Mass density and weight
density
, Mass/Weight Density Correct Answer-Mass Density commonly used for
SI units
g/cm3 or kg/m3
Weight Density commonly used for U.S. Customary units
lb/in.3 or lb/ft3
Balance—measures mass Correct Answer-Uses objects of known mass
to find the unknown mass of an object
Measurement is unaffected by difference in gravity
Scale—measures weight Correct Answer-Measures force caused by
gravity
Measurement is affected by difference in the acceleration of gravity
May display a "mass" measurement reading by using an assumed
acceleration of gravity to convert from weight to mass
Volume: Measurement Correct Answer-Volume is the amount of three
dimensional space enclosed by an object.
Finding Volume:
Calculate using geometry of object
Measure indirectly using water displacement (or 3D scanner)
Surface area Correct Answer-is the sum of all the areas of the faces of a
three-dimensional solid.
