Mechanical Flashcards
(52 cards)
The only type of pulleys that provide mechanical advantage
Moveable pulleys
Formula for gear revolutions
r x d = R x D
r = revolutions
d = # of teeth
r/d = Gear A
R/D = Gear B
Hydrometers use ______ to measure ________.
Hydrometers use floats to measure specific gravity.
Specific gravity
Specific gravity is the ratio of the density of a substance to the density of a reference substance.
In a hydrometer, the liquid with the ________ _________ ________ will cause the float to rise higher in the glass tube.
In a hydrometer, the liquid with the highest specific gravity will cause the float to rise higher in the glass tube.
First-class lever
Fulcrum is in the middle
E.g. scissors, pliers
Second class lever
Fulcrum is at one end, load is in middle
E.g. nutcracker, wheelbarrow
Third class lever
Fulcrum is at one end, effort is in between
E.g. tongs, tweezers
When spinning together, which pulley spins faster, the small or large one?
The small one – it has to keep up
Formula for mechanical advantage in pistons
(Smaller displacement)/(Larger displacement) = MA
a1 x d1 = a2 x d2
a = area
d = displacement
An axe is, in mechanical terms:
A wedge, i.e. an inclined plane.
Voltimeter
Tells the total voltage in a circuit.
Is a burnt-out light bulb a circuit?
No, but a voltimeter can bypass it if connected to both ends.
In an electrical series, current and voltage do what?
Current stays constant, voltage does not.
In an electrical parallel
Current changes; voltage does not.
Formula for voltage
V = I x R
Voltage = (current) x (resistance)
A series has greater resistane because its current must pass through _______.
resistors
In a 2-pulley system, the movable pulley will only move up _________ the distance and spin ________ as much as the fixed pulley.
In a 2-pulley system, the movable pulley will only move up half the distance and spin half as much as the fixed pulley.
To find RPM of wheel with rods:
Take the needed contacts per minute and divide that by the # of rods on the wheel.
E.g. need 120 contacts per minute, have 10 rods =
120/10 =
12 RPM
The closer to the center of a driver wheel that an adjacent wheel is present, the _______ it will move.
The closer to the center of a driver wheel that an adjacent wheel is present, the **faster **it will move.
The deeper you go underwater with an inflated ball, the more _______ it becomes.
The deeper you go underwater with an inflated ball, the more **buoyant **it becomes.
Rate of heat exchange is ______ through objects of greater temperature difference.
Rate of heat exchange is **faster **through objects of greater temperature difference.
If you place an object evenly on 2 scales, each scale will read _______ of the total weight.
If you place an object evenly on 2 scales, each scale will read **half **of the total weight.
The 4 strokes of a 4-stroke engine:
Intake
Compression
Combustion
Exhaust
