What it shows
Carrom players sprinkle fine powder on the board to make the striker glide. Measuring how far a striker slides with and without powder shows how a thin layer lowers friction.
The science
Friction opposes sliding. The fine powder grains act like tiny ball bearings between the striker and board, which lowers the friction. A striker leaving the ramp at the same speed slides farther on the smoother surface before friction stops it.
Materials
Cost: free. Many items come from home or from waste; spare parts such as LEDs, motors and wire are in the store.
- A carrom board and a striker
- Boric-free carrom powder or fine talcum
- A measuring tape along the board edge
- A small ramp made of a book
- A cloth to wipe the board
- A notebook
Safety
For this project: Do not breathe in the powder or put it near eyes; an adult should handle and clean it, and hands should be washed after use.
Never use mains electricity: power models with cells, batteries or a low-voltage adapter. Sharp and hot tools, flames and lab chemicals need an adult or your teacher beside you. Keep magnets, button cells and small parts away from young children, and wash your hands after making.
All the safety rulesStep by step
8 steps. Do them in order, and test each part before you go on to the next. Write what you notice in a notebook as you go.
Wipe the board clean and dry and set the ramp at one edge.
Release the striker from the same mark on the ramp so it always leaves with the same speed.
Measure the distance it slides along the board before it stops.
Repeat five times on the clean board and average the results.
Sprinkle a thin, even layer of powder on the board and wipe off the excess.
Repeat the release five times and record the new distances.
Try twice the amount of powder and check if the sliding distance keeps growing.
Draw a bar chart of the three conditions and find the percentage increase in distance.
What you should see
The striker slides farther with a thin layer of powder, and too much powder can make no further difference or can even slow it by piling up.
Viva questions
A teacher or a judge will ask how it works. Try to answer each question before you open it, then compare.
1Why does powder help the striker slide?
The grains reduce direct contact and so the friction.
2Why release from the same mark?
To give the same starting speed.
3What is the control in this test?
The clean board with no powder.
4What other things reduce friction?
Oil, water films and rolling instead of sliding.
Take it further
Estimate the coefficient of friction from the sliding distance and the release speed.
Change one thing, measure what happens, and add a table or chart of your readings: that is what turns a model into your own investigation.
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