Mechanical Engineering is part of Engineering and holds 2,078 questions with answers, free to read and with no account needed.
Attempt each question before revealing the answer, and keep a note of the ones you get wrong — those are the topics worth reading about properly. If an answer looks wrong, there is a link to report it on every question.
Answer: A. temperature
Specific heat values of real gases like air increase as the system temperature rises significantly. Higher temperatures activate additional molecular rotational and vibrational energy storage modes within gases. This inc...
Answer: D. process is isentropic and specific heat does not change with temperature
An isentropic process represents a reversible adiabatic expansion or compression of a gas. When specific heats remain constant across temperature ranges, the polytropic index equals gamma. Under these specific conditions...
Answer: B. conservation of energy
The first law mandates that energy input must equal energy output plus storage. It rules out the possibility of creating perpetual motion machines of the first kind. Energy transforms between heat, work, and internal for...
Answer: C. normal temperature and pressure
NTP is an internationally recognized acronym used to define standard ambient laboratory reference conditions. It establishes baseline values for temperature and pressure to allow consistent comparison of experimental dat...
Answer: B. heat is supplied to water at temperature below the maximum temperature of the cycle
The Rankine cycle heats liquid water to its saturation temperature incrementally before vaporization occurs inside the boiler. Carnot vapor cycles would ideally add all thermal energy isothermally at the maximum cycle te...
Answer: B. does not depend on the mass of the system, like temperature, pressure, etc
Intensive properties, such as temperature, pressure, and density, are independent of system mass. Dividing a system in half does not alter the intensive property values within each half. These properties define the local...
Answer: D. watt
Power is defined as the rate at which work is performed or energy is transferred over time. In the International System of Units, power is measured in watts, honoring inventor James Watt. One watt is formally equivalent...
Answer: B. joule
The International System of Units designates the joule as the standard unit for energy. Work and energy share identical dimensional units in classical mechanical calculations. One joule represents the energy transferred...
Answer: C. 0.24
Experiments measure the heat required to raise air temperature at constant pressure. For standard atmospheric air, this specific heat value is roughly 0.24 kcal/kg C. It represents a fundamental property used in psychrom...
Answer: B. decrease
In a regenerative Brayton cycle, raising the pressure ratio increases the compressor exit temperature. When this compressor discharge temperature exceeds the turbine exhaust temperature, the regenerator can no longer tra...
Answer: A. Avogadro’s hypothesis
Amedeo Avogadro proposed that equal volumes of ideal gases contain identical numbers of molecules under similar conditions. Equal molecular weights represent proportional amounts of substance that occupy the exact same p...
Answer: C. Atkinson cycle
The Atkinson cycle features heat addition at constant volume and heat rejection at constant pressure. This specific combination allows the expansion ratio to exceed the compression ratio. Higher expansion extracts more e...
Answer: E. temperatures of source and sink
Carnot engine efficiency is derived exclusively from the absolute temperatures of the thermal source and sink. Mathematical formulas for Carnot efficiency contain only the high and low absolute temperature variables. The...
Answer: A. a temperature of – 273.16°C
Absolute zero temperature represents the complete cessation of molecular motion in matter. At this theoretical temperature of minus 273.16 degrees Celsius, absolute pressure reaches zero. This point defines the absolute...
Answer: D. heterogeneous system
Ice and water mixtures contain two distinct physical phases interacting together. Solid ice represents one phase while liquid water represents another phase. Systems with multiple physical phases are classified as hetero...
