The Ultimate Mechanics Quiz! Trivia

1.

How many revolutions of the crankshaft are in a complete cycle for a 2-stroke-cycle engine?
- A.
  
  0
- B.
  
  1
- C.
  
  4
- D.
  
  12
Correct Answer
B. 1

Explanation
In a 2-stroke-cycle engine, a complete cycle occurs with just one revolution of the crankshaft. This is because the engine completes the intake, compression, power, and exhaust strokes in just two strokes of the piston, which corresponds to one revolution of the crankshaft. Therefore, the correct answer is 1.

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2.

The crankshaft has large lobes that act as counterweights, continuing centrifugal force to keep the crank turning after the explosion of the fuel.
- A.
  
  True
- B.
  
  False
- C.
  
  Not enough info given
Correct Answer
A. True

Explanation
The given statement is true. The crankshaft in an engine is designed with large lobes that act as counterweights. These counterweights help to balance the rotating assembly and reduce vibrations. Additionally, the counterweights also play a crucial role in maintaining the crankshaft's momentum after the explosion of fuel in the combustion chamber. The centrifugal force generated by the rotating crankshaft helps to keep it turning smoothly, ensuring the engine's continuous operation.

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3.

Three key differences between the diesel and the gasoline 4-stroke-cycle engines are: Diesel is heavier construction, Diesel has a higher compression ratio, and _______
- A.
  
  Diesel always uses a carburetor
- B.
  
  Diesel combustion occurs because of intense heat and pressure added to the fuel and air
- C.
  
  Gasoline combustion requires a fuel injector to create the spark
- D.
  
  Diesel engines have oversized spark plugs D. diesel engines have oversized spark plugs D. diesel engines have oversized spark plugs
Correct Answer
B. Diesel combustion occurs because of intense heat and pressure added to the fuel and air

Explanation
In diesel engines, the air is compressed first, and then the fuel is injected. Because air heats up when it’s compressed, the fuel ignites. This is different from gasoline engines, where fuel is mixed with air, compressed by pistons, and ignited by sparks from spark plugs. So, the three key differences between diesel and gasoline 4-stroke-cycle engines are: Diesel engines are heavier in construction, diesel engines have a higher compression ratio, and diesel combustion occurs because of intense heat and pressure added to the fuel and air.
Please note that diesel engines do not use carburetors or spark plugs, and gasoline combustion does not require a fuel injector to create the spark. These are common misconceptions. Diesel engines use direct fuel injection, and it’s the heat of the compressed air that ignites the fuel1. Gasoline engines, on the other hand, use spark plugs for ignition.

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4.

Air-cooled small gas engines are cooled by:
- A.
  
  Oil
- B.
  
  fins
- C.
  
  Flywheel
- D.
  
  Air
- E.
  
  All of the above E. all of the above all of the above
Correct Answer
E. All of the above E. all of the above all of the above

Explanation
Air-cooled small gas engines are cooled by a combination of oil, fins, flywheel, and air. Oil helps to lubricate the engine and also absorbs heat, which aids in cooling. Fins are designed to increase the surface area of the engine, allowing for better heat dissipation. The flywheel also helps in cooling by acting as a fan and circulating air around the engine. Finally, air plays a crucial role in cooling the engine by carrying away the heat generated during combustion. Therefore, all of the options mentioned (oil, fins, flywheel, and air) contribute to the cooling of air-cooled small gas engines.

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5.

The four strokes in order for a 4-stroke-cycle engine are
- A.
  
  Intake, compression, power, exhaust
- B.
  
  Intake, exhaust, power, compression
- C.
  
  Exhaust exhaust intake power
- D.
  
  None of the above
Correct Answer
A. Intake, compression, power, exhaust

Explanation
The correct answer is intake, compression, power, exhaust. This is the correct order of the four strokes in a 4-stroke-cycle engine. During the intake stroke, the piston moves downward, allowing the intake valve to open and the fuel-air mixture to enter the combustion chamber. In the compression stroke, the piston moves upward, compressing the fuel-air mixture. The power stroke is when the spark plug ignites the compressed mixture, causing an explosion that drives the piston downward. Finally, in the exhaust stroke, the piston moves upward, pushing the exhaust gases out of the combustion chamber through the open exhaust valve.

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6.

A 2-stoke-cycle engine is likely to be found on
- A.
  
  Subcompact cars built in Greenland
- B.
  
  Chainsaws and weed trimmers
- C.
  
  Most lawnmowers and snowblowers D. most lawnmowers and snowblowers lawn mowers
Correct Answer
B. Chainsaws and weed trimmers

Explanation
A 2-stroke-cycle engine is likely to be found on chainsaws and weed trimmers because these tools require a lightweight and compact engine that can provide high power-to-weight ratio. 2-stroke engines are known for their simplicity, low weight, and high power output, making them suitable for handheld tools like chainsaws and weed trimmers. On the other hand, subcompact cars built in Greenland and most lawnmowers and snowblowers typically use 4-stroke engines, which are more fuel-efficient and produce less pollution.

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7.

To describe a 2-stoke-cycle engine function, understand that
- A.
  
  The piston lowers allowing exhaust to exit the exhaust port just prior to intake port opening to allow air/fuel/oil into the cylinder.
- B.
  
  The piston raises to the top allowing exhaust to exit the exhaust port just prior to intake port opening to allow air/fuel/oil into the cylinder
- C.
  
  The piston is attached to the head by the valve keeper.
Correct Answer
A. The piston lowers allowing exhaust to exit the exhaust port just prior to intake port opening to allow air/fuel/oil into the cylinder.

Explanation
The correct answer is the first statement: "The piston lowers allowing exhaust to exit the exhaust port just prior to intake port opening to allow air/fuel/oil into the cylinder." This statement accurately describes the function of a 2-stroke-cycle engine, where the piston moves downwards to expel exhaust gases through the exhaust port, creating space for the intake port to open and allow the mixture of air, fuel, and oil to enter the cylinder. This process is essential for the engine to function properly and generate power.

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8.

Two parts of the camshaft are: timing gear and
- A.
  
  Cam shaft teeth
- B.
  
  Coil
- C.
  
  Cam lobes
Correct Answer
C. Cam lobes

Explanation
The camshaft is a crucial component of an engine that controls the opening and closing of the valves. It consists of several parts, including the timing gear and cam lobes. The timing gear is responsible for synchronizing the rotation of the camshaft with the crankshaft, while the cam lobes are the raised surfaces that push against the valves to open and close them. These lobes have specific shapes and sizes to create the desired valve timing and lift, allowing for efficient combustion and power generation in the engine.

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9.

A _____________________________ or supercharger uses the exhaust to blow in more air into the cylinder.
- A.
  
  Diablo chip
- B.
  
  Turbo
- C.
  
  Flywheel
Correct Answer
B. Turbo

Explanation
A turbocharger uses the exhaust to blow in more air into the cylinder. This increases the amount of air available for combustion, resulting in more power being produced by the engine. The turbocharger is driven by the flow of exhaust gases, which causes a turbine to spin. This turbine is connected to a compressor, which compresses the incoming air and forces it into the cylinder at a higher pressure. This allows the engine to burn more fuel and generate more power.

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The Ultimate Mechanics Quiz! Trivia

How many revolutions of the crankshaft are in a complete cycle for a 2-stroke-cycle engine?

The crankshaft has large lobes that act as counterweights, continuing centrifugal force to keep the crank turning after the explosion of the fuel.

Three key differences between the diesel and the gasoline 4-stroke-cycle engines are: Diesel is heavier construction, Diesel has a higher compression ratio, and _______

Air-cooled small gas engines are cooled by:

The four strokes in order for a 4-stroke-cycle engine are

A 2-stoke-cycle engine is likely to be found on

To describe a 2-stoke-cycle engine function, understand that

Two parts of the camshaft are: timing gear and

A _____________________________ or supercharger uses the exhaust to blow in more air into the cylinder.