Why do sidewalks have small gaps between the concrete sections?
ATo save concrete
BTo let rain drain through
CTo give the concrete room to expand when it gets hot
DTo make the sidewalk look nice
The gaps are expansion joints. Without them, concrete would push against itself when it expands in hot weather and could crack or buckle.
Question 2 True / False
When a solid is heated, its particles move farther apart.
TTrue
FFalse
Answer: True
Heating gives particles more energy, causing them to vibrate faster and push farther apart. This is why the material expands.
Question 3 Short Answer
What happens to a metal bridge on a very hot summer day?
Think about your answer, then reveal below.
Model answer: The metal expands slightly, making the bridge a little longer.
Heat causes the metal atoms to vibrate more and spread apart. Engineers include expansion joints in bridges to give the metal room to grow without causing damage.