Forces You Can Name: teacher key

Pushes and Pulls, grade 5 edition, written for 5th grade. Gravity, friction and drag all act on things that move. Meet the forces, and meet Galileo and Newton, who worked out how forces change motion.

Read the book. Print this page for the key.

Questions and answers

1. What is a force?
   • A kind of speed
   • A push or a pull (answer)
   • A heavy thing
2. What slows a thing that moves through air or water?
   • Drag (answer)
   • Gravity
   • A bigger push
3. Why does it take more force to start a heavy crate sliding than to keep it sliding?
   • The crate gets heavier as it moves
   • Gravity gets weaker once it moves
   • Friction on a still thing is bigger than on a moving thing (answer)
4. Who lived from 1564 to 1642?
   • Isaac Newton
   • Galileo (answer)
   • A skydiver
5. A skydiver reaches terminal velocity. What is true then?
   • The speed stops changing (answer)
   • Gravity stops pulling
   • The skydiver speeds up faster
6. What is inertia?
   • A kind of sandpaper
   • A tendency to resist changes in motion (answer)
   • A force that works across a gap

Words

• force: push or pull
• friction: rubbing slowdown
• drag: slowing force
• inertia: resisting change