Physics
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Questions and Answers

What are the properties of solids?

Arranged in neat rows, fixed in place but vibrating, keeps in shape in a container and cannot be compressed

What are the properties of liquids?

Still touching but can move around, can be poured, takes the shape of a container and cannot be compressed

What are the properties of gases?

Fast moving, spread out meaning it can be compressed, fills the entire container

Define Density

<p>How much mass is in a given volume</p> Signup and view all the answers

What is the density equation?

<p>Density = mass/volume</p> Signup and view all the answers

Practical - Density (regular)

<p>→ Measure the height / width / length of the object and multiply them together ( if a cuboid ) to get the volume . For a prism / cylinder you would work out the cross sectional area then multiply it by the length . → Measure the mass of the object by using a mass balance → Divide the mass by the volume</p> Signup and view all the answers

Practical - Density (irregular)

<p>→ Measure the mass of the object by using a mass balance → Measure the volume of the object by using a displacement can and a measuring cylinder → The volume of the water which is displaced out of the displacement can into the measuring cylinder when the object is added is the volume of the object → Divide the mass by the volume</p> Signup and view all the answers

What are the three main types of energy transfer?

<p>Conduction, convection and thermal radiation</p> Signup and view all the answers

How does heat travel?

<p>From a hot place to a cold place</p> Signup and view all the answers

What will a hot drink do in a room?

<p>cool down (C)</p> Signup and view all the answers

What will a cold drink do in a room?

<p>Warm up (A)</p> Signup and view all the answers

What type of wave is infrared radiation?

<p>Electromagnetic</p> Signup and view all the answers

Electromagnetic waves can travel through a vacuum as no particles are involved

<p>True (A)</p> Signup and view all the answers

The hotter the object...

<p>the more thermal radiation it emits</p> Signup and view all the answers

What do we use to see infrared radiation?

<p>thermal image camera</p> Signup and view all the answers

The type of surface affects...

<p>how much thermal radiation it absorbs or emits</p> Signup and view all the answers

Types of surfaces and what they are used for

<p>Good absorber and emitter = Black and Matt Bad absorber(good reflector) poor emitter = White and silver/smooth Why are houses in Spain white? = Reflect the thermal radiation, keeping them cool Why are solar panels black? = Absors thermal radiation so water heats up quicker</p> Signup and view all the answers

Investigate how the amount of infrared radiation absorbed or radiated by a surface depends on the nature of that surface .

<ol> <li>Pour 200cm³ of hot water into the silver can and the same volume in the black can</li> <li>Record the starting temperature of water in each can</li> <li>Record the temperature of each can every minute for 10 minutes</li> <li>At the end , calculate the temperature drop for the water in each can .</li> <li>Compare your results to your hypothesis and write a conclusion</li> </ol> Signup and view all the answers

Conduction doesn't need particles so it can travel through a vacuum

<p>False (B)</p> Signup and view all the answers

Where does conduction work best?

<p>In solids as the particles are close together</p> Signup and view all the answers

Where does conduction work worst?

<p>In gases as the particles are far apart</p> Signup and view all the answers

How do particles pass energy in a solid?

<p>Particles gain energy so they vibrate more. This makes them collide with their neighbouring particles. The collisions pass the energy from one particle to the next.</p> Signup and view all the answers

What makes metals fantastic conductors?

<p>they contain free electrons. The free electrons can diffuse quickly along the metal taking heat energy with them.</p> Signup and view all the answers

What are bad conductors called?

<p>Insulators e.g. plastic and wood</p> Signup and view all the answers

How to reduce conduction?

<p>Use either a vacuum (no particles no conduction) or some trapped air as it is a bad conductor e.g. vacuum flask, double glazing and duvet/clothes.</p> Signup and view all the answers

How to reduce radiation?

<p>Silver surfaces reflect the radiation back onto the hot object e.g. Space blankets, wrapping hot food in tin foil</p> Signup and view all the answers

Factors affecting heat loss

<p>-Surface area - bigger more heat loss</p> <ul> <li>Material the object is made from (conductor or not)</li> <li>Surface the object is on (again conductor or not)</li> </ul> Signup and view all the answers

Which factor does NOT affect heat loss?

<p>The shape of the object (B)</p> Signup and view all the answers

How do animals' ears affect heat loss?

<p>big ears, large surface area, lots of heat transfer so good in the desert and small ears, small surface area, small heat transfer so good in cold places</p> Signup and view all the answers

The bigger the temperature difference...

<p>the bigger the heat transfer</p> Signup and view all the answers

How does the roof nsulated the house?

<p>Fibre glass insulation (reduces conduction and convection)</p> Signup and view all the answers

Hwo do windows insulate the house?

<p>Double-glazing (reduces conduction because of the air gaps inbetween the glass)</p> Signup and view all the answers

What affects how much heat is lost through walls?

<p>The thickness and thermal conductivity of the walls</p> Signup and view all the answers

How do the walls insulate the house?

<p>Cavity fibre glass (gap between walls filled with insulating fibre glass contains trapped air which cannot move so no convection)</p> Signup and view all the answers

How does the floor insulate the house?

<p>Carpet and underlay (poor conductor)</p> Signup and view all the answers

How does the door insulate the house?

<p>UPVC (poor conductor)</p> Signup and view all the answers

How does the humble draught excluder insulate you house?

<p>Prevents draughts caused by convection</p> Signup and view all the answers

Define payback time

<p>how long you have to wait to save back money on your energy bills compared to how much it cost to buy.</p> Signup and view all the answers

payback time equation

<p>payback time = cost of insulation/energy bill savings</p> Signup and view all the answers

The sooner the insulation pays for itself...

<p>the more cost effctive it is</p> Signup and view all the answers

Chemical energy

<p>Released during chemical reactions (like when a fuel is burnt)</p> Signup and view all the answers

Kinetic energy

<p>All moving objects have kinetic energy (more speed more kinetic energy)</p> Signup and view all the answers

Gravitational potential energy

<p>Stored energy that objects get as they are moved upwards against the force of gravity</p> Signup and view all the answers

Elastic potential energy

<p>Stored energy when an elastic material is stretched or squashed (springs back to original shape)</p> Signup and view all the answers

Internal energy

<p>the total kinetic and potential energy all of the particles have in a system</p> Signup and view all the answers

Thermal energy

<p>the amount of internal energy due to temperature</p> Signup and view all the answers

Nuclear energy

<p>Energy stored in the nucleus</p> Signup and view all the answers

What does it mean when energy is conserved?

<p>Energy at the start = Energy at the end</p> Signup and view all the answers

Energy cannot be created or destroyed

<p>True (A)</p> Signup and view all the answers

What pathways do we use to convert energy?

<p>Mechanical (moving the object), electricity (using a current to transfer the energy, radiation (light sound etc) and heating by conduction</p> Signup and view all the answers

How do we reduce friction?

<p>using a lubricant</p> Signup and view all the answers

Wasted energy

<p>energy that you do not want the device to do</p> Signup and view all the answers

Useful energy

<p>the energy you do want from the device</p> Signup and view all the answers

What does wasted energy do?

<p>spreads out into the surroundings around the device (dissipates).</p> Signup and view all the answers

Efficiency equation

<p>Efficiency = useful energy output/ total energy input</p> Signup and view all the answers

Power, energy and time equation

<p>Power (W) = Energy (J)/Time (S)</p> Signup and view all the answers

What does power tell you?

<p>the amount of energy transferred in a second</p> Signup and view all the answers

Flashcards

Solid State of Matter

Matter with a fixed shape and volume, where particles are closely packed.

Liquid State of Matter

Matter with a fixed volume but a changing shape, particles are close together but can move past each other.

Gas State of Matter

Matter without a fixed shape or volume, particles are widely spaced and move freely.

Density

Mass per unit volume

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Density Equation

Density = mass / volume

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Conduction

Heat transfer by direct particle collisions, mainly in solids.

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Convection

Heat transfer by the movement of fluids (liquids and gases).

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Radiation

Heat transfer by electromagnetic waves, can travel through a vacuum.

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Infrared Radiation

A type of electromagnetic radiation that transfers heat.

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Heat Loss

Energy transfer from a warmer object to a cooler one.

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Heat Loss Factors

Temperature difference, surface area, and insulation affect heat loss.

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Energy Efficiency

Effectiveness of using energy to get work done.

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Payback Time

Time for an energy-saving investment to pay for itself.

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Energy Conservation

Energy cannot be created or destroyed, only transformed.

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Study Notes

Properties of Matter

  • Solids have a fixed shape and volume, and their particles are closely packed.
  • Liquids have a fixed volume, but their shape changes, and their particles are close together but can move past each other.
  • Gases have neither a fixed shape nor volume, and their particles are widely spaced and can move freely.

Density

  • Density is a measure of mass per unit volume.
  • The density equation is: density = mass / volume.
  • Density can be measured for regular and irregular shapes.

Energy Transfer

  • There are three main types of energy transfer: conduction, convection, and radiation.
  • Heat travels through conduction, convection, and radiation.
  • A hot drink in a room loses heat, decreasing the temperature, while a cold drink gains heat, increasing the temperature.
  • Infrared radiation is a type of electromagnetic wave.
  • Electromagnetic waves, including infrared radiation, can travel through a vacuum.

Infrared Radiation

  • The hotter the object, the more infrared radiation it emits.
  • We use thermographic cameras or thermal imaging devices to see infrared radiation.
  • The type of surface affects how much infrared radiation it absorbs or radiates.
  • Different surfaces are used for different purposes, depending on their ability to absorb or radiate infrared radiation.

Conduction

  • Conduction does not need particles, so it can travel through a vacuum.
  • Conduction works best in solids, where particles are closely packed.
  • Conduction works worst in gases, where particles are widely spaced.
  • In a solid, particles pass energy through direct collisions.
  • Metals are fantastic conductors because of their free electrons.
  • Bad conductors are called insulators.
  • Conduction can be reduced by using insulators, increasing the distance between particles, or decreasing the temperature difference.

Heat Loss

  • Factors affecting heat loss include temperature difference, surface area, and insulation.
  • The bigger the temperature difference, the faster the heat loss.
  • Animals' ears help reduce heat loss by minimizing exposed surface area.
  • Roofs, windows, walls, floors, and doors can be insulated to reduce heat loss.
  • The humble draught excluder helps reduce heat loss by blocking cold air.

Energy Efficiency

  • Payback time is the time it takes for an investment to pay for itself through energy savings.
  • The payback time equation is: payback time = cost / annual energy savings.
  • The sooner the insulation pays for itself, the better the investment.

Energy Types

  • Energy types include chemical, kinetic, gravitational potential, elastic potential, internal, thermal, and nuclear energy.
  • Energy is conserved, meaning it cannot be created or destroyed, only converted from one type to another.
  • Energy pathways include conversion from one type to another, such as from kinetic to thermal energy.

Energy Efficiency and Friction

  • Friction can be reduced by using lubricants, streamlining shapes, or using bearings.
  • Wasted energy is the energy lost as heat or sound due to friction or other inefficiencies.
  • Useful energy is the energy that is transferred or converted into a useful form.
  • The efficiency equation is: efficiency = useful energy / total energy.
  • The power, energy, and time equation is: power = energy / time.
  • Power tells you the rate at which energy is transferred or converted.

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