Question

In a gasoline engine, fuel vapors are ignited by a spark. In a diesel engine, a fuel-air mixture is drawn in, then rapidly compressed to as little as 1/20 the original volume, in the process increasing the temperature enough to ignite the fuel-air mixture.

Part A
Explain why the temperature rises during the compression

Answer 1

Here's what I get

Step-by-step explanation:

ΔE = q + w

The compression cycle is so fast that heat doesn't have time to enter or leave the cylinder.

Thus, q is constant.

When you compress the gas, you are doing work on it and increasing the internal energy (mostly kinetic) of its molecules.

Temperature is a measure of the average kinetic energy of the molecules, so the temperature rises during compression.