ASTB Mechanical Comprehension, Questions and answers, 100% Accurate, rated A

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ASTB Mechanical Comprehension, Questions and answers, 100% Accurate, rated A Which pulleys provide mechanical advantage? - ✔✔-movable Formula for gear revolutions - ✔✔-r(revolutions) x d... (number of teeth) = R x D Pulley mechanical advantage - ✔✔-number of parts of the rope that act on the load Note about mechanical advantage: - ✔✔-mechanical advantage is gained by combining a fixed pulley with a moveable pulley or another fixed pulley of a different diameter What are hydrometers? - ✔✔-They use floats to measure specific gravity What is specific gravity? - ✔✔-the weight of a liquid compared with the weight of water. the liquid with the highest specific gravity will cause the float to rise higher in the glass tube The lower the density of the substance... - ✔✔-...the farther the hydrometer will sink. first class lever - ✔✔-fulcrum in the middle (scissors, pliers) second class lever - ✔✔-fulcrum is at one end, load is in between (nutcracker, wheelbarrow) third class lever - ✔✔-fulcrum is at one end, effort is in between (tongs, tweezers) Which turns faster? small or big pulley? - ✔✔-smaller pulley will turn faster than those larger than it. it has to "keep up" and therefore turns faster. mechanical advantage in pistons - ✔✔-a2 x d2 = a1 x d1 (smaller D)/(bigger D) = mechanical advantage axe is a... - ✔✔-wedge, which is an inclined plane Fulcrum Resistance Arm Info? - ✔✔-the farther away the fulcrum is from the resistance arm, the greater the amount of force that is required to lift the weight and the higher the resistance arm will travel Voltimeter? - ✔✔-Measures total voltage in a circuit Does electricity flow through burnt out bulbs? - ✔✔-No, but a voltimeter can bypass it if connected on both sides. Series: current and voltage - ✔✔-current is constant in series, voltage is not Parallel: current and voltage - ✔✔-voltage is constant, current is not Voltage formula - ✔✔-V=I*R (voltage = current*resistance) Which circuit usually has the greater resistance? - ✔✔-The circuit with the greater resistance is usually in series, because it forces the current through all resistors. what happens to the moveable pulley in a 2 pulley system? - ✔✔-the moveable pulley will only move up half the distance, and spin half as much as the fixed pulley to find a necessary rpm - ✔✔-take number of rods on the wheel, and divide by the number of contacts per minute (for example, twice per second = 120 contacts per minute. 10 projection rods on wheel. 120/10 = 12. must rotate at 12 rpm) Driver wheel and adjacent wheels - ✔✔-if a driver wheel is present, the adjacent wheels will rotate according to how close to the center the driver wheel makes contact with them. the closer to the center, the faster it will move. Increase length of lever arm, and then increase the effort. what happens? - ✔✔-enable a valve to blow off at a higher pressure. move the weight further away to do this. (if a lever causes less effort it lets its valve blow up at a lower pressure) micrometer - ✔✔-sometimes known as a micrometer screw gauge. device incorporating a calibrated screw used widely in precise measurement of small distances. remember wiki pictures of how to read how does string length affect time - ✔✔-the one pendulum with the longer string takes the longest to complete 1 swing Pendulums and weight - ✔✔-the weight doesn't matter for swing time. if string length is the same, swing time is the same. board in water with weights - ✔✔-if a board is placed in the water with 1 weight at each end, the end with the weight closest to the center will tend to float more than the one furthest from the center bar with weights on string - ✔✔-if weights hang from a string attached to a bar, less pull is exerted by the weight of less weight. the length of string doesn't matter. buoyancy - ✔✔-the deeper you go with an inflated ball, the more difficult it is to hold it under water. the deeper you go with the same ball, the more buoyant the ball is. when is rate of exchange faster? - ✔✔-it is faster through objects of greater temperature difference when does water flow faster? - ✔✔-faster through narrow areas than wider areas? think of putting your thumb on the end of a hose to make it spray... how does narrow/wider affect amount of flow? - ✔✔-the same amount of water will flow through the smaller and larger part of the pipe in a given time what happens with object on 2 scales? - ✔✔-if placed evenly, each scale will read half of the total weight. 4 stroke engine - ✔✔-intake, compression, combustion, exhaust [Show More]

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