Energy Revision and Science Report Writing

Comprehensive practice question-and-answer flashcards covering energy concepts (kinetic, potential, thermal, sound, chemical, and light), energy conservation and efficiency calculations, and science report writing structure.

What is energy, and what is its standard unit of measurement?

Energy is defined as the ability to do work and is measured in joules ($\text{J}$).

What must happen to energy in order to produce changes?

Energy needs to be moved to a different location or changed into a different form.

What two factors determine an object's kinetic energy?

Mass (the heaviness of the object) and speed (how fast it is moving).

What is the formula for calculating kinetic energy, and what do the variables represent?

$E_k = \frac{1}{2}mv^2$, where $m$ represents mass and $v$ represents velocity or speed.

What consequences does an object having more kinetic energy have when moving?

More kinetic energy makes the object harder to stop and results in more impact.

What does the Law of Conservation of Energy state?

"Energy can neither be created nor destroyed, but can change from one type to another."

According to the Law of Conservation of Energy, how does total input energy relate to total output energy?

Total input energy equals total output energy (e.g., $100\,\text{J}$ electrical = $60\,\text{J}$ light and $40\,\text{J}$ heat).

How is total energy calculated using kinetic and gravitational potential energy?

$$\text{KE} + \text{GPE} = \text{total energy}$$

What are the three ways thermal energy can be transferred?

Conduction, convection, and radiation.

How does conduction transfer heat, and in what state of matter does it occur?

Heat is transferred through the vibration of neighbouring particles; it occurs in solids (with metals being the best conductors, and air and wool/foam acting as poor conductors or insulators).

What is convection, and in what states of matter does it occur?

Convection is heat transfer through the movement of particles in the form of currents, and it occurs in liquids and gases.

How does radiation transfer heat?

Heat transfers through empty space using electromagnetic waves, with no need for particles or matter.

How is sound produced and how does it travel?

Sound is produced when matter vibrates, and these vibrations travel outwards from the source in longitudinal waves.

How do particles move in a longitudinal sound wave?

Particles move back and forth in the same direction that the wave is travelling.

What makes up one sound wave, and how is wavelength defined?

One wave consists of one compression and one rarefaction; the distance from one compression to another is a wavelength.

What is frequency in sound, and how does it relate to pitch?

Frequency is how often a compression passes a certain point in one second; higher frequency corresponds to higher pitch, and lower frequency corresponds to lower pitch.

Why is it impossible for sound to be heard in outer space?

Sound travels through a medium and cannot travel in a vacuum where there are no particles.

Through which state of matter does sound travel the fastest and why?

Solids, because the particles in solids are closely packed together.

Why does sound travel faster through a hot medium than a cold medium?

Particles in a hot medium have more energy, causing them to vibrate and collide more, which transfers sound more quickly.

What is elastic energy?

The energy that is stored in stretched or compressed objects (more stretch/compression equals more energy).

What is chemical energy, and how is it stored and released during reactions?

Chemical energy is the potential of chemicals inside an object to react; it is stored in bonds between atoms, requires energy to break existing bonds, and is released when new bonds form.

Where is chemical potential energy (CPE) stored in food?

It is stored in the fats, sugars, and proteins of food.

What is the difference between an energy transfer and an energy transformation?

In an energy transfer, energy stays in the same form but moves from one place or object to another; in an energy transformation, one type of energy changes to another type.

What are the key properties of light energy listed in the notes?

It travels in straight waves, is part of the electromagnetic spectrum, travels faster than sound, and can be reflected, refracted, or absorbed.

How do reflection, refraction, and absorption of light differ?

Reflection is when light bounces off a surface; refraction is when light changes direction as it passes through a material; absorption is when light is taken in by a material instead of being reflected or transmitted.

What is the formula for calculating energy efficiency?

$$\text{energy efficiency} = \frac{\text{useful output energy}}{\text{total input energy}} \times 100$$

If an electrical device receives $250\,\text{J}$ of energy and produces $200\,\text{J}$ of light energy and $50\,\text{J}$ of heat energy, what is its efficiency?

$\frac{200}{250} \times 100 = 80\%$ useful energy.

What do Sankey diagrams illustrate?

They show energy efficiency, where arrows represent the proportion of the diagram that is useful or waste energy.

What mandatory structure must be used when writing a hypothesis?

"If (IV) then (DV)"

What are independent, dependent, and controlled variables in an experiment?

The independent variable is the factor the experimenter changes; the dependent variable is the factor the experimenter wants to measure; controlled variables are factors kept the same.

What four elements must be included in a report conclusion?

1. Restate aim and whether the hypothesis was rejected or not; 2. Summarise results and data; 3. Explain the science behind what happened (the why); 4. Identify errors and future improvements.

What are the three components of the CER structure in report writing?

Claim (what you claim to be), Evidence (data and results supporting that claim), and Reasoning (explanation of how and why that evidence supports the claim).