Tablecloth trick
Explore how gravity, friction and motion work together to produce an amazing tablecloth trick!
This activity may be Messy and Noisy
Explore how gravity, friction and motion work together to produce an amazing tablecloth trick!
This activity may be Messy and Noisy
What will I need?
Top tip
There’s a high chance that while you’re practising this trick, the crockery might go flying. Be sure to try this in a space with enough safe room around the table and warn anyone nearby of what you’re about to do. Also, don’t use your best teapot and cups in case they do break!
Gather your supplies using the list above.
1.
Place the shiny tablecloth on the table, leaving half of the cloth hanging over the side (make sure the table has no rough edges).
2.
Put the cups and teapot on the tablecloth at the edge of the cloth. Make sure the tablecloth doesn’t have a raised hem.
3.
Grasp the overhanging part of the tablecloth in your hands tightly. Before you pull, make sure the cloth is still smooth and there aren’t any air bubbles underneath.
4.
In one fast movement, pull the tablecloth towards you and down. The cups and teapot should stay where they are!
- What would happen if you used a different fabric for the tablecloth?
- What about if the cups were heavier or lighter? Does this affect the trick?
- Does the speed you pull out the tablecloth make any difference?
The tablecloth and the table are both smooth – there isn’t much friction between the two. So when the tablecloth is pulled away, it can slide out easily from under the crockery. The only force acting on the cups and teapot is gravity, pulling them down onto the table. This trick helps us understand inertia. Inertia is the tendency for an object to remain at rest until a force acts on it. As there is no external force pushing or pulling on the cups and teapot, they stay where they were.
Inertia can be experienced in lots of everyday situations. When you are standing in a moving bus you lean forward when the brakes are applied suddenly. This is because your body is in motion along with the bus. When the bus stops quickly, the lower part of your body comes to rest along with the bus, whereas the upper part of your body continues to move forwards.
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