A spark plug fires before the gases in a cylinder are fully compressed. How will the engine be affected?

A. The engine will get better gas mileage as less fuel is burned during each cycle.
B. There will be fewer pollutants as the fuel has more time to burn.
C. The gases will do less work to the piston because the gases cannot expand as much.
D. The engine will not get hot because the ratio of work to heat will increase.

3 answers

the answer was c

1.D

To determine the correct answer, let's analyze the situation. A spark plug fires before the gases in a cylinder are fully compressed.

When a spark plug fires before the gases are fully compressed, it means that the combustion process is occurring earlier than expected in the engine's cycle. This is known as pre-ignition or knocking.

Now, let's evaluate the options:

A. The engine will get better gas mileage as less fuel is burned during each cycle.

This option is incorrect because pre-ignition can cause incomplete combustion, leading to lower fuel efficiency due to wasted fuel.

B. There will be fewer pollutants as the fuel has more time to burn.

This option is also incorrect. When pre-ignition occurs and combustion happens earlier, it can cause inefficient combustion, resulting in higher levels of unburned fuel and the potential for increased pollutants.

C. The gases will do less work to the piston because the gases cannot expand as much.

This option is correct. When pre-ignition occurs, the combustion happens before the piston reaches its peak compression, reducing the work done by the expanding gases on the piston. This can result in a decrease in engine power and performance.

D. The engine will not get hot because the ratio of work to heat will increase.

This option is incorrect. Pre-ignition does not directly affect the engine's temperature or the work-to-heat ratio. Instead, it can lead to increased heat due to inefficient combustion, which can potentially cause damage to engine components.

So, the correct answer is C. The gases will do less work to the piston because the gases cannot expand as much.