# Lesson Worksheet: Engine Performance Physics

In this worksheet, we will practice calculating a variety of measures of power and efficiency of internal combustion engines.

**Q1: **

An engine contains six cylinders that each complete 18 cycles of pressure and volume changes per second. The indicated power of the engine is 33 kW. Find the work done by a cylinder per cycle to the nearest joule.

**Q2: **

An engine has a brake power of 22 kW. The engine produces a torque of 350 Nā m. Find the angular speed of the engine approximated to nearest radian per second.

**Q3: **

An engine produces a torque of 280 Nā m and has an angular speed of 23 rad/s. Find the brake power of the engine to the nearest watt.

**Q4: **

An engine has an indicated power of 25 kW. When the engine runs, the power that it dissipates by friction is 1.25 kW.

Find the brake power of the engine to the nearest watt.

Find the mechanical efficiency of the engine to the nearest percent.

**Q5: **

An engine has a mechanical efficiency of and a brake power of 17 kW. Find the indicated power of the engine to the nearest watt.

**Q6: **

The graph shows the changes in pressure and volume that occur in the cylinder of a gas engine over one cycle. The work done during the cycle . An engine contains four of these cylinders, and each of the cylinders completes 5 cycles of pressure and volume changes per second. Find the indicated power of the engine to the nearest watt.

**Q7: **

The fuel combusted in an engine releases 45 MJ of energy per kilogram. The engine combusts 0.75 grams of fuel per second. The indicated power of the engine is 13,360 W.

Find the input power to the engine to the nearest watt.

Find the thermal efficiency of the engine to the nearest percent.

**Q8: **

Which of the following statements correctly relates the mechanical efficiency , thermal efficiency , and overall efficiency of an engine ?

- A
- B
- C
- D
- E