In most four-stroke internal combustion engines, when does the piston move upward?

a. during the compression stroke only

b. during the compression and exhaust strokes

c. during the intake and exhaust strokes

d. during the power and intake strokes

C. during the intake and exhaust strokes

Explanation:

In four stroke engine one complete cycle of gas is completed in four strokes

Two compression strokes

Two expansion strokes

In first expansion stroke the engine will intake air and mix it into the fuel

while in its other expansion stroke it will exhaust all the burnt gases from the engine.

so here in this four stroke engine when piston moves up then due to expansion piston moves up and correct answer for it is

C. during the intake and exhaust strokes

hot magma rises and pushes up toward the lithosphere, and as it cools it cycles back down toward the core to be heated again.