Question

1) The piston of an oil engine of area 0.0045 m² moves downward 75 mm, drawing in
0.00028 m² of fresh air from the atmosphere. The pressure in the cylinder is uniform
during the process at 80 kPa, while atmospheric pressure is 101.325 kPa, the
difference being due to the flow resistance in the induction pipe and the inlet valve.
Estimate the displacement work done by the air finally in the cylinder.​

Answer 1

Answer:

Volume of piston stroke = 0.0045 × 0.075m3 = 0.0003375m3

∴ΔV = 0.0003375 m3

as pressure is constant = 80 kPa

So work done = pΔV = 80 ×0.0003375 kJ = 0.027 kJ = 27 J

Answer 2

Volume of piston stroke = 0.0045 × 0.075m³

                                          = 0.0003375m³

                                ∴ΔV = 0.0003375 m³

Here the pressure is constant = 80 kPa

So work done = pΔV

                        = 80 ×0.0003375 kJ

                        = 0.027 kJ

                        = 27 J