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Sample Practice Test Questions
Which of the following nuts use a pin to lock the nut in place and prevent it from loosening?
slotted
Wrenches are used with threaded fasteners like bolts and nuts. A bolt has external threads while a nut has internal threads and this thread pattern combination allows them to lock together and act as fasteners. Nuts come in a variety of configurations including wing nuts which provide appendages that allow tightening and loosening by hand, slotted nuts that use a cotter pin to lock the nut in place and prevent it from loosening, and lock nuts that also prevent loosening via nylon in their threads. Threads are identified by pitch which is the number of threads per inch.
Which of the following is not true of a first-class lever?
decreases distance
A first-class lever is used to increase force or distance while changing the direction of the force. The lever pivots on a fulcrum and, when a force is applied to the lever at one side of the fulcrum, the other end moves in the opposite direction. The position of the fulcrum also defines the mechanical advantage of the lever. If the fulcrum is closer to the force being applied, the load can be moved a greater distance at the expense of requiring a greater input force. If the fulcrum is closer to the load, less force is required but the force must be applied over a longer distance. An example of a first-class lever is a seesaw / teeter-totter.
The force exerted on an object due to gravity is called:
weight
Mass is an intrinsic property of matter and does not vary. Weight is the force exerted on the mass of an object due to gravity and a specific case of Newton's Second Law of Motion. Replace force with weight and acceleration with acceleration due to gravity on Earth (g) and the result is the formula for weight: W = mg or, substituting for g, weight equals mass multiplied by 9.8 m/s2.
If the green arrow in this diagram represents 420 ft⋅lb of work, how far will the box move if it weighs 140 pounds?
Win = Wout
Feffort x deffort = Fresistance x dresistance
In this problem, the effort work is 420 ft⋅lb and the resistance force is 140 lbs. and we need to calculate the resistance distance:
Win = Fresistance x dresistance
420 ft⋅lb = 140 lbs. x dresistance
dresistance = \( \frac{420ft⋅lb}{140 lbs.} \) = 3 ft.
Which of the following is not a terminal on a transistor?
input
A transistor works by allowing a small amount of current applied at the base to control general current flow from collector to emitter through the transistor.
In a four-stroke piston cycle, one piston is always:
all of these are correct
In a four-stroke cycle engine there is always one piston delivering power, one exhausting gases, one drawing in the air-fuel mixture, and one compressing that mixture.
Resistance is opposition to which of the following?
current
Resistance is opposition to the flow of current and is measured in ohms (Ω). One ohm is defined as the amount of resistance that will allow one ampere of current to flow if one volt of voltage is applied. As resistance increases, current decreases as resistance and current are inversely proportional.
A fixed pulley is useful for which of the following?
changing the direction of the input force
A fixed pulley is used to change the direction of a force and does not multiply the force applied. As such, it has a mechanical advantage of one. The benefit of a fixed pulley is that it can allow the force to be applied at a more convenient angle, for example, pulling downward or horizontally to lift an object instead of upward.