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Sample Practice Test Questions
The spark plugs fire a few extra degrees before top dead center when the engine is running faster. In this case the engine's timing is:
advanced
Ignition timing defines the point in time at the end of the compression stroke that the spark plug fires. Measured in number of degrees before top dead center (BTDC), the exact point that the spark plugs initiate combustion varies depending on the speed of the engine. The timing is advanced (the spark plugs fire a few more degrees BTDC) when the engine is running faster and retarded when it's running slower.
The dimensions of this cube are height (h) = 7, length (l) = 7, and width (w) = 7. What is the surface area?
The surface area of a cube is (2 x length x width) + (2 x width x height) + (2 x length x height):
sa = 2lw + 2wh + 2lh
sa = (2 x 7 x 7) + (2 x 7 x 7) + (2 x 7 x 7)
sa = (98) + (98) + (98)
sa = 294
What is the primary difference between a rectifier and an inverter?
a rectifier converts an AC input to DC while an inverter converts a DC input to AC
A diode allows current to pass easily in one direction and blocks current in the other direction. Diodes are commonly used for rectification which is the conversion of alternating current (AC) into direct current (DC). Because a diode only allows current flow in one direction, it will pass either the upper or lower half of AC waves (half-wave rectification) creating pulsating DC. Multiple diodes can be connected together to utilize both halves of the AC signal in full-wave rectification.
The pitch of the siren of an approaching ambulance changes as it approaches you. This is an example of which of the following?
Doppler effect
The Doppler effect occurs when the source or listener (or both) of sound waves is moving. If they're moving closer together, the listener perceives the sound with a higher pitch and, when they're moving apart, the listener perceives the sound with a lower pitch.
Which of these is the formula for force?
F = ma
Newton's Second Law of Motion states that "The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object." This Law describes the linear relationship between mass and acceleration when it comes to force and leads to the formula F = ma or force equals mass multiplied by rate of acceleration.
Which of the following enables heat transfer from the cylinder heads to the coolant?
water jacket
A water jacket is a coolant-filled casing that allows heat transfer from the engine block and cylinder heads to the liquid coolant.
Which of the following expressions contains exactly two terms?
binomial
A monomial contains one term, a binomial contains two terms, and a polynomial contains more than two terms.
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.