Work = The Amount of energy transferred by a force The word “Work” was first coined by French...
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• Work = The Amount of energy transferred by a force • The word “Work” was first coined by French mathematician Gaspard-Gustave Coriolis in 1830 • The work-Energy theorem is: If an external force is applied to an object causing its kinetic energy to change, then work has been done. & W = F x d (Force) (Distance) Work = ∆E k (Change in kinetic energy) Engine, work & power
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Transcript of Work = The Amount of energy transferred by a force The word “Work” was first coined by French...
• Work = The Amount of energy transferred by a force
• The word “Work” was first coined by French mathematician Gaspard-Gustave Coriolis in 1830
• The work-Energy theorem is: If an external force is applied to an object causing its kinetic energy to change, then work has been done.
&W = F x d
(Force) (Distance)
Work = ∆Ek
(Change in kinetic energy)
Engine, work & power
• Horsepower: Coined by James Watt in ~1787• When a horse could turn a mill wheel 144 times
an hour (2.4 times per minute) the wheel had a 12ft radius, so traveled 2.4x2xpix12ft in one minute.
• He figured intellectually that a horse could pull 180 pounds continuously, so:
• In reality a very optimistic value but it helped him sell steam engine.
Power (HP) = Work / Time = (Force x Distance) / Time= (180lbs)x(2.4x2xpix12ft)/ Time= 32572 (ft.lbs)/min= 542.8 (ft.lbs)/sec
Engine, work & power
Point of maximum volumetric efficiency
Horsepower curve
RPM0
100
500
400
300
200
0 1000 2000 3000 50004000 70006000 8000
HP
peak
Engine, work & power
Area under the curve = total work done.
To maximize acceleration (and efficiency) run the engine as much as possible in this range.
Engine, work & power
Horsepower curve
RPM0
100
500
400
300
200
0 1000 2000 3000 50004000 70006000 8000
HP
peak
Spring Computation
MM
KSpring
KTire
Spring Computation
BA
BABA KK
KKK
KB
M
KA
Total stiffness when 2 springs are in series:
Spring Computation
BA
BABA KK
KKK
KB
M
KA
Total stiffness when 2 springs are in series:
KA = 1600 lbs/inKB = 1200 lbs/inKA+B = (1600 x 1200)/(1600 + 1200)KA+B = 686 lbs/in
Spring Computation
KC
M
KA
Total stiffness when 2 springs are in series and in parallel:
CBA
CBACBA KKK
KKKK
KB
Spring Computation
Total stiffness when 2 springs are in series and in parallel:
CBA
CBACBA KKK
KKKK
KC
M
KA
KBKA = 1600 lbs/inKB = 700 lbs/in KC = 1200 lbs/inKA+B+C = ((1600+700) x 1200)/((1600+700) + 1200)KA+B+C = 789 lbs/in
Spring Computation
Area under the curve = total work done.
Spring Force - deflection Curve
Distance
0 0.2 0.4 0.6 1.00.8 1.41.2 1.6
0
500
2500
2000
1500
1000
Force
Time
-100
-75
-50
-25
0
25
50
75
100
0 5 10 15 20 25 30Am
plit
ude
Time
Spring decaying oscillations
Spring Under Damped
Spring Normally Damped
Spring Over Damped
Spring decaying oscillations
“Spring Under Damped” Work=
“Spring Normally Damped” Work=
“Spring Over Damped” Work=
Spring decaying oscillations
If Damping , then Spring Work
Spring decaying oscillations
Spring with no damping
Spring dampedShock damping work
