Body Temperature, Energy and Heat Loss MCQs

By what means does a person sitting in the shade of a tree on a very hot dry summer day lose most of their heat? By:

Radiation

Conduction

Convection

Evaporation

On a hot day, sweating will be occurring, and its evaporation into a dry atmosphere would produce cooling. As the surroundings and air are hot, not much heat will be lost by radiation, convection or conduction.

Author: rikazzz Comment

Body Temperature, Energy and Heat Loss

What may the “thermal energy” of the particles in an object be defined as?

The amount of heat that is contained in the object.

Sum of the random translational, rotational and vibrational kinetic energies.

Sum of the random translational, rotational and vibrational kinetic energies and the work done to overcome the intermolecular forces.

Average random kinetic energy of the particles.

In gases, thermal energy is energy stored as kinetic energy, rotational motion, vibrational motion and associated potential energies. In other substances, in cases where some of the thermal energy is stored in atomic vibration or by increased separation of particles having mutual forces of attraction, the thermal energy is partitioned between potential energy and kinetic energy.

Author: rikazzz Comment

Body Temperature, Energy and Heat Loss

What is the reason that the temperature of a substance does not rise while it is in the act of melting, even if heat is added to it?

Melting will not occur until the latent heat of vaporisation has been sup-plied; this prevents a rise in temperature until all the solid has melted.

The added heat energy is used to increase the vibrational and rotational kinetic energies rather than the temperature (i.e. translational kinetic energy) of the particles.

The presence of colder unmelted particles alongside particles that are in liquid form causes their temperature to remain low.

Any energy added to the substance is used to break the bonds that hold the particles into the solid form so it does not contribute to a temperature rise.

Once the bonds between the adjacent particles of a solid have been broken, they are free to move about, and the particles can increase their kinetic energy, that is, the rise in temperature.

Author: rikazzz Comment

Body Temperature, Energy and Heat Loss

Which of the following is the most acceptable definition of the term “power”?

The rate of doing work

That which is stored and can be fully recovered and converted to kinetic energy

The concept applied to that which gives an object the ability to do work

The sum of an object’s potential and kinetic energies

Power refers to how fast work is done. That is, the time taken for the energy in joules to be used. The unit of power is the “watt” which is the same as joules per second.

Author: rikazzz Comment

Body Temperature, Energy and Heat Loss

Why does perspiring cause heat energy to be lost from the body? Because:

Being at a lower temperature than the skin, sweat cools skin by conduction.

Evaporating water molecules remove heat in the form of their own kinetic energy.

The presence of sweat on the skin prevents infrared radiation being absorbed.

Sweat on the skin allows heat to be lost to the air by conduction.

Vaporising water molecules carry away more than the average kinetic energy. Temperature of an object is the average kinetic energy of its particles. The skin surface is left at a lower temperature.

Author: rikazzz Comment

Body Temperature, Energy and Heat Loss

Hyperthermia is a core body temperature greater than which of the following temperatures?

36 °C

37 °C

38 °C

39 °C

38 is the lower limit of what is considered to be a fever in a resting adult.

Author: rikazzz Comment

Body Temperature, Energy and Heat Loss

What is heat? It is a:

Measure of the temperature of an object

Transfer of energy by convection currents

Measure of the average translational kinetic energy of the particles

Form of energy transfer along a temperature gradient

Heat is the energy that is transferred between two objects due to their difference in temperature. Choice C refers to the temperature of an object.

Author: rikazzz Comment

Body Temperature, Energy and Heat Loss

Which is the correct distinction between temperature and heat?

Temperature is a measure of the amount of heat in an object, and heat is the energy that flows between objects which have different temperatures.

Heat is a measure of the energy contained within an object, and temperature is the objective measurement of heat.

Temperature is a measure of the average kinetic energy of particles, and heat is the energy that flows between objects as a result of a temperature difference.

Heat is the energy that flows from a cold object to a hotter object, and temperature measures the average random kinetic energy of the particles.

Heat flows from the object at higher temperature to the object at lower temperature. Choices A and B are nonsensical in their reference to temperature.

Author: rikazzz Comment

Body Temperature, Energy and Heat Loss

What does kinetic theory allows us to understand that the temperature of an object measures? The:

Heat that it contains

Average kinetic energy of its particles

Hotness or coldness of it

Number of degrees Kelvin it is

All particles of an object move or vibrate. Temperature is the average kinetic energy of the particles of an object.

Author: rikazzz Comment

Body Temperature, Energy and Heat Loss

When the label on a packaged food item states that 100 g contains 650 kJ of energy, it means that:

The human body is able to extract 650 kJ of heat and useful work by digesting the food.

650 kJ of energy was consumed in growing or producing or making the food.

650 kJ of heat energy is released when 100 g of the food is burned in an atmosphere of pure oxygen.

Ultimately your body will be able to perform 650 kJ of work for every 100 g of the food that you eat.

Food energy values are determined by burning a sample of the food in a calorimeter and measuring the heat produced. If the body was 100% efficient, choice A would be true.

Author: rikazzz Comment