Question

the thermal energy in a heat engine is used to move a piston. which best describes why this is possible?
the increase in thermal energy results in an increase in pressure.
the decrease in thermal energy results in an increase in pressure.
the increase in thermal energy results in a decrease in pressure.
the decrease in thermal energy results in a decrease in pressure.

Explanation:

When thermal energy increases in a heat - engine (like when fuel is burned), the gas molecules gain kinetic energy. According to the ideal gas law \(PV = nRT\) (where \(P\) is pressure, \(V\) is volume, \(n\) is the amount of gas, \(R\) is the gas constant, and \(T\) is temperature), if the volume \(V\) (assuming a fixed - volume chamber initially) and \(n\) are constant, an increase in \(T\) (which is related to thermal energy) leads to an increase in \(P\). The increased pressure then acts on the piston to move it.

Answer:

The increase in thermal energy results in an increase in pressure.