P4 Heat (Concept Map)
Primary 4 Science — Concept Map
Created by Miss Clarissa Ng · www.clartutors.com
Heat — a form of energy that flows from hot to cold
Where heat comes from, how it moves, and what it does to objects
Heat is a form of energy, and the Sun is the main source of heat on Earth.
Temperature = how hot or cold something is. Heat energy = the amount of energy, which depends on mass or volume and temperature.
Heat flows from a region of higher temperature to a region of lower temperature: gain heat → temperature rises; lose heat → temperature falls.
Metals are good conductors and transfer heat quickly; wood, plastics, rubber and air are poor conductors.
Heat gain expands an object and can change its state (melting, boiling); heat loss contracts it (freezing, condensation) — mass stays the same.
Sources of heat
The Sunthe main source of heat on Earth — it heats the Earth from far away
Other natural sourcesvolcanoes and geysers give out heat from inside the Earth
Burning fuels and electricityfirewood, charcoal and gas give out heat as they burn, and electricity gives out heat too
Temperature
How hot or coldthe temperature of an object tells you its degree of hotness, in degrees Celsius (°C)
Measured witha thermometer, or a datalogger with a temperature sensor
Heat energyheat is the amount of energy, which depends on mass or volume and temperature
Heat flows from hot to cold
Hot to coldheat flows from a region of higher temperature to a region of lower temperature until both are the same
Gain or lose heatan object that gains heat increases in temperature; one that loses heat decreases in temperature
Cooling downhot water left out loses heat to the surroundings and cools to room temperature
Good and poor conductors
Good conductorsmetals such as iron and copper conduct heat quickly, so they also cool down quickly
Poor conductorsair, wood, plastics and rubber conduct heat slowly
Why we use thempoor conductors of heat keep a cold drink cold and a hot drink warm for longer
Effects of heat gain and loss
Expansion and contractionan object that gains heat expands; one that loses heat contracts. The mass stays the same
The ink-drop flaskair in a flask gains heat and expands, pushing the ink drop up; in ice water it contracts
Change of stateheat gain melts or boils; heat loss condenses or freezes
Heat around us
Train trackson a hot day the tracks gain heat and expand; they can buckle, so gaps are left between the rails
Telephone lineshung slack so that on a cold day they lose heat, contract and tighten instead of snapping