Heat and Work

Heat flows spontaneously from hot objects to

• Hot objects

• 
  Cold objects

• Any object

• Undefined

Answer explanation

Heat flows spontaneously from hot objects to cold objects because heat is a form of energy that naturally moves from regions of higher temperature to regions of lower temperature. This is known as the second law of thermodynamics. When two objects of different temperatures are in contact, the heat energy will transfer from the hotter object to the colder object until both objects reach thermal equilibrium.

0.605 m³ of gas is inside a piston that is stuck in place. A pressure of 1.50 x 10⁴ Pa is applied to the piston, and the piston doesn't budge. How much work was done?

• 4.03 x 10^-5 J

• 24793 J

• 0 J

• 9075 J

Answer explanation

Since the piston is stuck in place, it means that there is no displacement and therefore no work is done. Work is defined as the product of force and displacement in the direction of the force. In this case, the force is applied but there is no displacement, so the work done is zero.

A gas expands and does 215 J of work on a piston. The gas exerts a pressure of 1230 Pa on the piston. What is the change in the volume of the gas?

• 0.175 m³

• 5.72 m³

• 2.64 x 10⁵ m³

• 12.1 m³

Answer explanation

The work done by a gas is given by the equation W = PΔV, where W is the work done, P is the pressure, and ΔV is the change in volume. Rearranging the equation, we can solve for ΔV by dividing both sides by P: ΔV = W/P. Plugging in the given values, ΔV = 215 J / 1230 Pa = 0.175 m3. Therefore, the change in volume of the gas is 0.175 m3.

Which of the following equations is the equation for calculating the work done by a gas in a piston?

• W=Fd

• W=PΔV

• A=πr²

• ΔV=Ad

Answer explanation

The equation W=PΔV represents the work done by a gas in a piston. This equation relates the work done (W) to the pressure (P) and the change in volume (ΔV) of the gas. The work done by a gas in a piston is equal to the product of the pressure and the change in volume.

The energy stored in gasoline is

• Electromagnetic energy

• 
  Nuclear energy

• 
  Mechanical energy

• Chemical energy

Answer explanation

Gasoline is a fossil fuel made up of hydrocarbon compounds. When gasoline is burned, these compounds undergo a chemical reaction with oxygen, releasing energy in the form of heat and light. This energy is stored in the chemical bonds of the hydrocarbons, making it chemical energy.

Temperature is associated with the average kinetic energy of the particles in an object due to their random motions through space.

• True

• False

Answer explanation

The statement is true because temperature is a measure of the average kinetic energy of the particles in an object. As particles move randomly through space, they possess kinetic energy, which is directly related to their temperature. The higher the temperature, the greater the average kinetic energy of the particles. Therefore, temperature is indeed associated with the average kinetic energy of the particles in an object.

Which of the following statements is true according to the law of conservation of energy?

• Energy cannot be destroyed

• Energy cannot be created

• 
  Energy can be converted from one form to another

• 
  All of the above

Answer explanation

According to the law of conservation of energy, energy cannot be created or destroyed, but it can be converted from one form to another. This means that the total amount of energy in a closed system remains constant. Therefore, all of the given statements are true.

Define work.

• Energy in transition not associated with mass transfer and due to temperature difference

• The energy transfer associated with a force acting through a distance

• energy that is transferred between two systems (or a system and its surroundings) by virtue of a temperature difference.

Example of work in a system

• A rising piston

• electric wire crossing the

  system boundaries

• A rotating shaft

• All the above

Find Tsat@100 kPa from the properties table.