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Sample Practice Test Questions
Which of these layers is found directly below the Earth's crust?
mantle
The crust is the Earth's outermost layer and is divided into oceanic and continental types. Oceanic crust is 3 miles (5 km) to 6 miles (10 km) thick and is composed primarily of denser rock. Continental crust is 20 to 30 miles (30 to 50 km) thick and composed primarily of less dense rock. The crust makes up approximately one percent of the Earth's total volume.
Respiration is the process by which __________ absorb oxygen and eliminate carbon dioxide.
blood cells
The respiratory system manages respiration which is the process by which blood cells absorb oxygen and eliminate carbon dioxide.
Concurrent forces:
pass through a common point
Collinear forces act along the same line of action, concurrent forces pass through a common point and coplanar forces act in a common plane.
Which of these is not a component of blood?
marrow
Blood is created in bone marrow and is made up of cells suspended in liquid plasma. Red blood cells carry oxygen, white blood cells fight infection, and platelets are cell fragments that allow blood to clot.
If the force applied at the blue arrow over 5 ft. moves the green box 2.5 ft., what is the mechanical advantage of this lever?
Mechanical advantage (MA) can be calculated knowing only the distance the effort (blue arrow) moves and the distance the resistance (green box) moves. The equation is:
MA = \( \frac{E_d}{R_d} \)
where Ed is the effort distance and Rd is the resistance distance. For this problem, the equation becomes:
MA = \( \frac{5 ft.}{2.5 ft.} \) = 2
You might be wondering how having an effort distance of 2 times the resistance distance is an advantage. Remember the principle of moments. For a lever in equilibrium the effort torque equals the resistance torque. Because torque is force x distance, if the effort distance is 2 times the resistance distance, the effort force must be \( \frac{1}{2} \) the resistance force. You're trading moving 2 times the distance for only having to use \( \frac{1}{2} \) the force.
Too much fuel results in a __________ air-fuel mixture that burns quicker and cooler.
rich
The stoichiometric ratio defines the proper ratio of air to fuel necessary so that an engine burns all fuel with no excess air. For gasoline fuel, the stoichiometric ratio is about 14.7:1 or for every one gram of fuel, 14.7 grams of air are required. Too much air results in a lean air-fuel mixture that burns more slowly and hotter while too much fuel results in a rich mixture that burns quicker and cooler.
A transformer utilizes an inductor to increase or decrease what in a circuit?
voltage
A transformer utilizes an inductor to increase or decrease the voltage in a circuit. AC flowing in a coil wrapped around an iron core magnetizes the core causing it to produce a magnetic field. This magnetic field generates a voltage in a nearby coil of wire and, depending on the number of turns in the wire of the primary (source) and secondary coils and their proximity, voltage is induced in the secondary coil.
Which of the following will increase the magnetic field produced by the electric current in a wire?
wind the wire into a coil
A moving electric current produces a magnetic field proportional to the amount of current flow. This magnetic field can be made stronger by winding the wire into a coil and further enhanced if done around an iron containing (ferrous) core.