Topic 1: Statics Flashcards
Crow bar
First-class lever, iron/steel bar used to wedge under an object to move or lift it
Bicycle
simple machine made of several components: axial, spoke, gear chain, crankshaft, pedals, vehicle used for transportation
Car jack
simple machine used as a lifting device
Linear motion
motion in a straight line
Rotary motion
motion in a circular path, motion about an axis
Oscillatory motion
motion that an object repeats continuously
Reciprocal motion
repetitive back-and-forth linear motion
Mechanical Advantage
MA=load/effort
Velocity Ratio
VR=distance moved by effort/distance moved by load
Efficiency
efficiency= MA/VR x100%
First class lever
Load-Fulcrum-Effort
Second class lever
Fulcrum-Load-Effort
Third class lever
Load-Effort-Fulcrum
Mechanical Advantage of Levers
MA=Load/Effort=distance to effort/distance to load
Velocity Ratio of Levers
VR=distance to effort/distance to load
Reducing Gears
the driver gear is smaller than the driven gear. Acts as a force multiplier but reduces speed
Multiplying Gears
the driver gear is bigger than the driven gear. Acts as a speed multiplier
Velocity ratio of Gears
VR=rpm of driver/ rpm of driven
Gear ratio of Gears
GR=driven/driver
Mechanical advantage of Gears
MA=GR
Efficiency of Gears
MA/VR or GR/VR
Velocity Ratio of Worm drives
VR=number of teeth on worm gear/threads on worm
Gear ratio of Rack and pinion
GR= pinion teeth/rack pitch
Mechanical Advantage of Inclined Planes
MA= load/effort
Velocity Ratio of Inclined Planes
VR=distance moved by effort (along plane)/distance moved by load (vertically up) = 1/sinx
Mechanical Advantage of Screws
MA= load/effort
Velocity ratio of Screws
VR= distance moved by effort/ distance mover by load= circumference/pitch
Pulleys
used to transmit power, change direction of force, provide assistance using MA
Velocity Ratio of First-order pulley system
VR=2^p, p=movable pulleys in system
Velocity Ratio of Second-order pulley system
VR=n, n= number of rops supporting lower pulleys
Mechanical Advantage of pulleys
efficiency x n or efficiency x 2^p
Work
W=Fd=Fdcosx=area under a force-displacement graph
Power
P=W/t=E/t=Fd/t
Potential Energy
PE=mgh
Kinetic Energy
KE=1/2*mv^2
Energy Efficiency
efficiency= useful output/input
Linear Motion
v=u+ at, v^2=u^2+as, s=ut+1/2*at^2, average velocity=s/t
Friction
force that opposes the motion of an object
Static Friction Force
force that keeps object at rest/just at the point of moving, F=coefficient of static friction x normal force
Kinetic Friction Force
force when there is relative motion.
F=coefficient of kinetic friction x normal force
coefficient of friction
coefficient of friction= friction force/normal force = tanx
limiting friction
frictional resistance that exists just as motion is about to occur
Angle of static friction (phi)
angle between resultant reaction and normal reaction
Angle of repose (theta)
angle of the inclined plane
