Download Principles of Engineering

Principles of Engineering
Name ____________________
Unit 1.1 – Mechanisms – Quiz
Date _______________
Matching – Which class of lever are the objects below? Match them. (1 point each)
A. 1st class lever
B. 2nd class lever
C. 3rd class lever
1. Shovel
_____
5. Stapler
_____
2. Scissors
_____
6. Broom
_____
3. Tweezers
_____
7. Hole Punch
_____
4. Wheelbarrow
_____
8. Hammer (removing a nail)
_____
Fill in the Blank – Write the word(s) that completes the sentence. (1 point each)
9. The input force supplied by the user or engine is known as __________________ .
10. The output force which is also the force resisting motion is known as __________________ .
11. The measure of how much effort is decreased by the simple machine is known as
___________________
___________________ .
12. According to the following thread note what does the 28 mean?
3/8 – 28 UNC
___________________
True or False – circle the correct answer (1 point each)
13.
The mechanical advantage of a 2nd class lever is always < 1.
T
F
14.
Ideal Mechanical Advantage (IMA) is calculated without friction.
T
F
Problems: Show all your work. Answer precision 0.0 (2 points each)
15.
A first class lever is balanced, and has a resistance of 75 pounds that is 3 feet from the
fulcrum. If the effort force is applied 10 feet from the fulcrum, how many pounds of
force were applied?
____________
16.
Suppose a wheel with an 8.5 inch radius is used to turn a water valve stem with a radius
of .65 inches. What is the Mechanical Advantage?
____________
17.
According to the diagram to the right, how many pounds of effort would be
needed to lift the weight?
__________
18.
According to the same diagram, How high would the weight rise if you
pulled 15 feet of rope?
__________
19.
A screw with 32 threads per inch is turned by a screwdriver having a handle
diameter of 1.5”. What is the mechanical advantage of this system?
__________
An inclined plane has a slope length of 11.5 feet and a vertical height of 4.5 feet.
20.
What is the Ideal Mechanical Advantage of the inclined plane?
__________
21.
22.
23.
What is the maximum load that can be moved with an effort of 45 pounds?
__________
Suppose that the user actually uses 50 pounds to move the above load. What is the
Actual Mechanical Advantage?
__________
What is the efficiency of this system?
A gear train contains the following:
__________
Gear A (input) 16 teeth
Gear B
24 teeth
Gear C (output) 36 teeth
24.
Gear C is turning at _______ RPM.
25.
Gear C is turning CW or CCW
48 rpm
CCW
A sprocket and chain mechanism has a drive gear diameter of 2 inches and a driven gear
diameter of 5 inches.
26.
What is the gear ratio?
27.
If the input speed is 250 rpm, what is the output rpm?
____________
____________
Simple Machines
Formulas
AMA 
IMA 
Variables
AMA = Actual Mechanical Advantage
FR = Resistance force
FE = Effort force
IMA = Ideal Mechanical Advantage
DR = Resistance Distance
DE = Effort Distance
FR
FE
DE
DR
LeverIMA 
LE
LR
Wheel and Axle IMA 
LE = Length from fulcrum to effort
LR = Length from fulcrum to resistance
rW
rA
rw = Wheel radius
ra = Axle radius
Pulley IMA = Total number of strands
supporting the load
Inclined Plane or Wedge MA 
L
T
C
ScrewIMA 
Pitch
1
Pitch 
TPI
Wedge IMA 
L
H
L = Slope length
H = Height
L = Slope length
T = Thickness
C = Circumference
Pitch = Screw pitch
TPI = Threads per inch
Gear Ratios
Formulas

GR  in
out
GR 
Nout
Nin
Nout dout



 in  out
Nin
din
out
in
Variables
GR = Gear ratio
ωin = Driver gear, rpm
ωout = Driven gear, rpm
Nin = Number of teeth on driver
Nout = Number of teeth on driven
din = Diameter of driver
dout = Diameter of driven
τin = Torque of driver, ft-lbs
τout = Torque of driven, ft-lbs