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A simple look at how different surfaces affect how things slide or roll.
Why does your toy car zoom like a rocket across the kitchen floor but stop suddenly when it hits the rug?
Think about a kitchen floor or a sidewalk. These surfaces are smooth. When a surface is smooth, it is flat and even. There are no big bumps to get in the way! When you give a toy a push on a smooth floor, it slides easily. Because the floor is so flat, the toy can keep going for a long time. It takes very little force to get it moving. If we gave the toy a push of unit of strength, it might travel floor tiles!
Let's look at how a block moves on a table: 1. Place a wooden block on a smooth table. 2. Give it a tiny push with one finger. 3. Watch it slide across the table easily because the surface is flat.
Quick Check
Is it easier to push a toy on a smooth floor or a floor with lots of bumps?
Answer
It is easier to push a toy on a smooth floor.
Now, think about a thick carpet or the green grass outside. These surfaces are bumpy. They have lots of little parts that stick up. When you try to slide something over them, those bumps rub against your toy. This rubbing is called friction. Friction is a force that pulls against the toy to slow it down. On a bumpy surface, you have to push much harder to keep the toy moving. If the bumps are big, the toy might stop almost immediately!
Imagine rolling a soccer ball in two places: 1. Roll the ball on a smooth sidewalk. It rolls a long way. 2. Roll the ball with the same push on thick grass. 3. The grass blades rub against the ball, creating friction, and the ball stops quickly.
Quick Check
What is the name of the rubbing force that slows things down on bumpy floors?
Answer
The rubbing force is called friction.
Imagine you have a big box of toys: 1. On the tile floor, you push with hands and it slides fast. 2. On the thick carpet, you push with hands but it doesn't move! 3. You must use your whole body to push harder to beat the friction of the carpet.
Which surface would make a toy car go the fastest?
What does friction do to a rolling ball?
You need to push harder to move a box on carpet than on a smooth hallway.
Review Tomorrow
Tomorrow, try to remember the word 'friction' and find one smooth surface and one bumpy surface in your house.
Practice Activity
Find a small toy car. Roll it on the kitchen floor, then roll it on a rug. Use a piece of tape to mark how far it goes each time!