Force & Motion — Answer Key
Part A: Fill in the Blank
Write the missing word or number on each line.
1. When two surfaces rub together, the force made is friction.
Friction is created when two surfaces rub against each other.
2. Rough surfaces usually have more friction than smooth ones.
Rough surfaces create more friction than smooth surfaces do.
3. A block slides farther on a smooth floor than on a rough rug.
A rough rug creates more friction, so the block stops sooner.
4. Ice is very smooth, so it has very little friction.
Smooth ice has low friction, letting things slide easily.
5. Sandpaper feels rough, so it has a lot of friction.
Sandpaper is rough and creates a lot of friction.
6. Friction turns motion into heat, which is why your hands get warm when you rub them.
Rubbing hands makes friction, which warms the skin.
7. A toy car rolls the farthest on a smooth floor.
Smooth floors create less friction, so cars roll farther.
8. Shoes with bumpy soles grip the ground because of friction.
Bumpy soles increase friction and help shoes grip.
9. On a slippery floor there is less friction, so you may slip.
Low friction means feet cannot grip and you may slip.
Part B: Matching
Match each item on the left to the correct answer on the right.
1. Match each item to its correct answer.
ice rink
→ sled glides far
sled glides far
sandpaper
→ block stops fast
block stops fast
waxed floor
→ socks slide easily
socks slide easily
grassy hill
→ ball rolls slowly
ball rolls slowly
Smooth surfaces let things glide while rough ones slow motion quickly.