Clothes peg
Friction
Crawling beetles/bugs
Make your own bugs as shown in the pictures.
Hang the ladybird to the door handle. Pull one or the other string to the side alternatively. The ladybird starts crawling upwards. When you release the string, the ladybird slides down.
Hold the spider in one hand while keep the other hand higher. When you stretch the string, the spider does not move, it stays at the same place. When you release the string, the spider moves down.
The Physics in this activity
If you pull the string to the sides, there is a friction between the straw and the string. The string pushes against the straw from inside. The friction prevents two things to slide. When you let the strings move, they stop pushing the straw, the friction gets smaller than before and the ladybird slides down.
The spider behaves similar way. When you tighten the string, it touches the straw, the friction increases and the spider stops moving. If you release the string, the friction between the string and the straw gets smaller than before and the spider can move again.
Which clothes peg is stronger?
You have many clothes peg. They have different sizes and properties. Which clothes peg is stonger?
Drill a hole in the clothes peg and tie a string. Catch the paper to clothes peg, then pull the twine with the force sensor in the opposite direction. After the start measurement the force senzor note down the "pulling force" into prepared graph. Find out the maximum of force and notes it.
Take another clothes peg and repeat the measurement. Compared maximum of forces.
Compare the friction between wood and other materials
In this activity we measure the friction between wood and other materials and we compare different cases.
Change the paper to another materials and compare the force-time graphs. Find the maximum of force.
In which case we measured the biggest friction? Between which of these materials?
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