What is kinetic energy?

Question

stored energy
the energy of motion
the energy of radiation
thermal energy

Answer 1

Kinetic energy is defined as the energy of motion. It is the energy that an object possesses due to its movement. The amount of kinetic energy an object has depends on its mass and its velocity and is calculated using the formula:

\[ KE = \frac{1}{2} mv^2 \]

where \( KE \) is kinetic energy, \( m \) is the mass of the object, and \( v \) is its velocity.

Answer 2

A fisherman in a boat is drinking a cup of hot coffee. The large lake below his boat is full of cold water. Which statement is an accurate comparison of the lake water and the coffee?
The lake will have more total thermal energy, and the particles in the lake water will be moving faster.
The lake will have more total thermal energy, but the particles in the coffee will be moving faster.
The coffee will have more total thermal energy, but the particles in the lake water will be moving faster.
The coffee will have more total thermal energy, and the particles in the coffee will be moving faster.

Answer 3

The accurate comparison between the lake water and the coffee is:

The lake will have more total thermal energy, but the particles in the coffee will be moving faster.

Here's why:

• Total Thermal Energy: Although the coffee is hot, the lake contains a much larger volume of water, which means it has a greater total amount of thermal energy. Thermal energy is the total energy of all the particles in a substance, and since the lake has vast quantities of water, its total thermal energy far exceeds that of the small cup of coffee.

• Particle Motion: The particles in the hot coffee are moving faster than those in the cold lake water. Higher temperature means greater particle motion, so the particles in the coffee have higher kinetic energy compared to those in the cooler lake water.

Answer 4

The gallium in the image is melting in the person's hand. Which changes will occur on a microscopic level?
The gallium atoms will increase in temperature.
The gallium atoms will gain potential energy, moving freely from each other.
The gallium atoms will gain kinetic energy.
The gallium atoms will be moving faster on average.

Answer 5

As the gallium melts in the person's hand, the following changes will occur on a microscopic level:

The gallium atoms will gain kinetic energy.

Here's the reasoning:

• Temperature Increase: While it's true that the gallium may also increase in temperature as it absorbs heat from the person's hand, the most direct change relevant to the melting process is that the atoms will gain kinetic energy.

• Freedom of Movement: As gallium transitions from a solid to a liquid state, the atoms gain enough energy to overcome some of the attractive forces holding them in fixed positions, allowing them to move more freely. This represents an increase in kinetic energy.

• Average Speed: Given that kinetic energy is directly related to the motion of the particles, it follows that the gallium atoms will indeed be moving faster on average as they transition from solid to liquid. However, the specific statement regarding kinetic energy directly addresses the change in energy associated with the melting process.

Overall, the most appropriate answer in this context is that the gallium atoms will gain kinetic energy as they melt.

Answer 6

Which object will have particles with the highest average kinetic energy?
water at 40°C in a swimming pool
an iceberg at 0°C
water at 37°C in a glass
a drop of water at 90°C

Answer 7

To determine which object has particles with the highest average kinetic energy, we can refer to the temperature of each object, as the average kinetic energy of particles is directly related to the temperature of a substance.

• Water at 40°C in a swimming pool
• Iceberg at 0°C
• Water at 37°C in a glass
• A drop of water at 90°C

Among these options, a drop of water at 90°C will have particles with the highest average kinetic energy.

Kinetic energy of particles increases with temperature; therefore, the higher the temperature, the greater the average kinetic energy of the particles. A drop of water at 90°C has the highest temperature compared to the other options, which means its particles have the highest average kinetic energy.

Answer 8

As water becomes warmer, boils and then becomes water vapor (steam), what happens to its kinetic and potential energies?
The particles will gain potential energy as it heats up, but the kinetic energy of the particles will stay the same.
The particles gain both potential and kinetic energy.
The kinetic and potential energies of the particles will stay the same.
The particles gain kinetic energy as it heats up, but the potential energy of the particles will stay the same.

Answer 9

The correct answer to the question about what happens to the kinetic and potential energies of water as it becomes warmer, boils, and then becomes water vapor (steam) is:

The particles gain both potential and kinetic energy.

Here's why:

1. Heating Up: As water warms up, the kinetic energy of the water molecules increases due to the increase in temperature. This means the particles are moving faster.

2. Boiling (Phase Change): When water boils, it undergoes a phase change from liquid to gas. During this phase change, the temperature remains constant, but the molecules gain potential energy as they overcome intermolecular forces to transition from liquid to gas. This is because energy is being added to break the bonds between the liquid particles.

3. Becoming Water Vapor (Steam): After the phase change is complete, as water vapor continues to be heated, its kinetic energy will increase further due to the rise in temperature, contributing to increased movement of the gas molecules.

Thus, throughout the process of heating, boiling, and becoming steam, both kinetic and potential energy of the water particles increase.