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Automotive Information

A cylinders acts as a guide for a:

piston

Cylinders act as a guide for the pistons that translate the heat energy of combustion into the mechanical energy necessary to move a vehicle. Piston rings seal the piston to the cylinder to contain combustion gases and also regulate the oil distribution between the piston and cylinder wall. A cylinder head closes in the top of the cylinder forming the combustion chamber which is sealed by a head gasket (head). The head provides space for air and fuel intake valves, exhaust valves, and mounts for spark plugs and fuel injectors.

Word Knowledge

Procrastinate most nearly means:

delay

To put off intentionally.

Arithmetic Reasoning

Which of the following is not a prime number?

A prime number is an integer greater than 1 that has no factors other than 1 and itself. Examples of prime numbers include 2, 3, 5, 7, and 11.

Mechanical Comprehension

Normal force is generally equal to the __________ of an object.

weight

Normal force arises on a flat horizontal surface in response to an object's weight pressing it down. Consequently, normal force is generally equal to the object's weight.

Word Knowledge

The flighty Caroline could not be troubled with mundane tasks such as paying her bills.

commonplace

Practical, ordinary.

General Science

The angle of reflection is equal to which the following?

angle of incidence

The law of reflection specifies how waves, including light waves, bounce off of surfaces. Specifically, the angle of incidence of the approaching wave is equal to the angle of reflection of the reflected wave as measured from a line perpendicular (90°) to the surface.

Mechanical Comprehension

If the green box weighs 25 lbs. and 75 lbs. of force is applied 5 ft. from the fulcrum at the blue arrow, how far from the fulcrum would the green box need to be placed to balance the lever?

15 ft.

To balance this lever the torques at the green box and the blue arrow must be equal. Torque is weight x distance from the fulcrum so the equation for equilibrium is:

R_ad_a = R_bd_b

where a represents the green box and b the blue arrow, R is resistance (weight/force) and d is the distance from the fulcrum.

Solving for d_a, our missing value, and plugging in our variables yields:

d_a = \( \frac{R_bd_b}{R_a} \) = \( \frac{75 lbs. \times 5 ft.}{25 lbs.} \) = \( \frac{375 ft⋅lb}{25 lbs.} \) = 15 ft.

Mechanical Comprehension

Which class of lever is used to increase force on an object in the same direction as the force is applied?

second

A second-class lever is used to increase force on an object in the same direction as the force is applied. This lever requires a smaller force to lift a larger load but the force must be applied over a greater distance. The fulcrum is placed at one end of the lever and mechanical advantage increases as the object being lifted is moved closer to the fulcrum or the length of the lever is increased. An example of a second-class lever is a wheelbarrow.

Word Knowledge

Sheila, who could not resist bragging, flaunted the "A" marked on her test paper.

parade

To display showily.

Automotive Information

What is the primary difference between internal and external combustion engines?

where the power is developed

The primary difference between internal and external combustion engines lies in where the power is developed. In an internal combustion engine fuel is ignited and burned inside the same container where the power is developed while in an external combustion engine the fuel is ignited outside the engine and the resulting power sent to it.