Thermodynamics and Engines

Which one of the following statements best describes a reversible process?

• All heat input into the system is converted into work during the process.
• The overall entropy of the system does not increase during the process.
• The initial and final temperatures for the process are the same.
• The entropy of the system decreases during the process.
• Statements (b) and (c) both describe a reversible process.

Which one of the following statements best describes the operation of a heat engine?

• A heat engine transfers heat from a higher temperature reservoir to a lower temperature reservoir through work performed on the system.
• A heat engine transfers heat from a lower temperature reservoir to a higher temperature reservoir through work performed on the system.
• A heat engine performs work and generates an equal amount of heat in a cyclic process.
• A heat engine decreases the entropy of the universe by generating an equal amount of heat and work.
• A heat engine uses input heat to perform work and rejects excess heat to a lower temperature reservoir.

Tags

NGSS.HS-PS3-4

Which one of the following statements concerning heat engines is false?

• A heat engine receives heat from a hot reservoir.
• A heat engine is a device that uses heat to do work.
• Heat engines generally operate near one hundred percent efficiency.
• Part of the heat input to the engine is used to do work by the working substance within the engine.
• Part of the input heat is rejected to a cold reservoir.

Tags

NGSS.HS-PS3-4

Which one of the following statements concerning an ideal engine is true?

• The entropy of the system decreases with time.
• No heat transfer occurs between the system and its surroundings.
• All system processes are reversible.
• The temperature of the system is usually constant.
• The system cannot be used to perform work.

Tags

NGSS.HS-PS3-4

An ice cube is placed on a table and begins to melt.  The following conclusion can be made.

• Energy is being absorbed by the table which causes the cube to melt.
• Energy is being transferred from the table to the ice cube.
• Energy is being created by the air and table and making the cube heat up.
• Energy  is being created by the ice cube and is being released to the air

Tags

NGSS.HS-PS3-4

The _____ Law of Thermodynamics says that heat always flows from an object with a higher temperature to an object of lower temperature naturally

• Zeroth
• First
• Second
• Third

Tags

NGSS.HS-PS3-4

As time progresses, Energy will naturally become more spread out.  It can only come together if you make it.

• Zeroth Law of Thermodynamics
• First Law of Thermodynamics
• Second Law of Thermodynamics
• Third Law of Thermodynamics

Tags

NGSS.HS-PS3-4

Heat flow from a cool body to a hot body would not violate the 1st Law, energy would be still conserved

• True

• False

• Maybe

• Sometimes

What is the efficiency of the machine if the input is 263 J and a the useful output is 142 J?

• 6.26%

• 54%

• 100%

• 260%

Tags

NGSS.HS-PS3-1

What is the work output of a machine that has a work input of 2,800 Joules and an efficiency of 92.3%? 

• 2,690J
• 92.3J
• 0.0082J
• 2,584.4