ASTB Mechanical Comprehension Exam Questions and Answers 100% Pass

ASTB Mechanical Comprehension Exam Questions and Answers 100% Pass 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) 2 | P a g e Katelyn Whitman© 2025, All Rights Reserved. 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) 3 | P a g e Katelyn Whitman© 2025, All Rights Reserved. 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.