1.
Heat moves from
Correct Answer
B. Warm to cool
Explanation
Heat moves from areas of higher temperature (warm) to areas of lower temperature (cool). This is because heat energy naturally flows from hotter objects to colder ones in an attempt to achieve thermal equilibrium. This process is known as heat transfer and occurs through conduction, convection, and radiation. Therefore, the correct answer is "warm to cool".
2.
If the atoms in an object begin to move faster, this indicates
Correct Answer
A. The object is heating up
Explanation
When the atoms in an object begin to move faster, it indicates that the object is heating up. This is because an increase in temperature causes the atoms to gain kinetic energy, leading to more rapid movement. As the atoms move faster, they collide with each other more frequently, transferring energy and causing the object to heat up. Therefore, the correct answer is that the object is heating up.
3.
If you mix 1 liter of 30 degrees C water with 1 liter of 70 degrees C water, the final temperature will be
Correct Answer
C. 50 degrees C
Explanation
When two substances of different temperatures are mixed together, they tend to reach a common temperature. This is known as thermal equilibrium. In this case, the 30 degrees C water and the 70 degrees C water will mix to reach a final temperature that is the average of the two initial temperatures. Therefore, the final temperature will be (30 + 70) / 2 = 50 degrees C.
4.
The average speed of the atoms in an ice cube are slow. This shows
Correct Answer
B. The temperature of the ice cube
Explanation
The average speed of the atoms in an ice cube being slow indicates the temperature of the ice cube. Temperature is a measure of the average kinetic energy of the particles in a substance. Since the atoms in the ice cube have slow average speed, it implies that they have lower kinetic energy, which corresponds to a lower temperature.
5.
Heat is created by
Correct Answer
C. The movement of atoms
Explanation
Heat is created by the movement of atoms. When atoms or molecules in a substance gain energy, they start to move faster and collide with each other. This movement transfers energy from one atom to another, resulting in the generation of heat. The more vigorous the movement of atoms, the higher the temperature and heat produced. Convection and conduction are both processes that involve the transfer of heat, but they are not the actual source of heat. They occur due to the movement of atoms, which is the fundamental cause of heat generation.
6.
Convection currents are created by
Correct Answer
A. Warm rising, cool sinking
Explanation
Convection currents are created by warm air or fluid rising and cool air or fluid sinking. When a substance is heated, its molecules gain energy and move faster, causing them to spread apart and become less dense. This warm, less dense substance then rises, creating a current. On the other hand, cool air or fluid is denser and sinks due to gravity. This process of warm rising and cool sinking creates convection currents.
7.
Earth's internal heat energy comes from
Correct Answer
B. The core and radioactive decay
Explanation
The correct answer is "the core and radioactive decay." The Earth's internal heat energy primarily comes from two sources: the core and radioactive decay. The Earth's core, composed of molten iron and nickel, generates heat through convection and the release of gravitational potential energy. Additionally, radioactive decay of elements such as uranium, thorium, and potassium within the Earth's crust also contributes to the internal heat. These processes continuously generate heat, maintaining the Earth's internal temperature and driving geological activities like plate tectonics and volcanic eruptions.
8.
Earth's surface heat comes from
Correct Answer
A. The sun and volcanoes
Explanation
The correct answer is the sun and volcanoes. The sun is the primary source of heat for the Earth's surface, as it emits vast amounts of energy in the form of sunlight. This solar energy warms the Earth's atmosphere and surface. Volcanoes also contribute to the Earth's surface heat through volcanic activity, which releases heat from the Earth's interior. Both the sun and volcanic activity play significant roles in maintaining the Earth's surface temperature.
9.
Radiation that leaves the Sun reaches the earth as
Correct Answer
D. All of the above
Explanation
The radiation that leaves the Sun reaches the earth in the form of visible light, ultraviolet light, and infrared radiation. Visible light is the portion of the electromagnetic spectrum that is visible to the human eye. Ultraviolet light has shorter wavelengths and is responsible for causing sunburns and other skin damage. Infrared radiation has longer wavelengths and is felt as heat. Therefore, all three types of radiation mentioned in the answer (visible light, ultraviolet light, and infrared radiation) reach the earth from the Sun.
10.
Solar radiation is mostly
Correct Answer
A. Visible light
Explanation
Solar radiation refers to the energy emitted by the sun in the form of electromagnetic waves. The sun emits a wide range of wavelengths, including visible light, ultraviolet light, and infrared radiation. However, the majority of solar radiation that reaches the Earth's surface is in the form of visible light. This is the light that is visible to the human eye and is responsible for providing illumination and enabling us to see our surroundings. Ultraviolet light and infrared radiation make up a smaller portion of solar radiation and have different effects and applications.