If you lay a steel needle horizontally on water, it will float. If you place the needle vertically into the water, it will sink. Explain why.
It is because of surface tension. The hydrogen molecules bond with the steel of the needle. Look up surface tension in wikipedia or something to help you better understand.
When a steel needle is placed horizontally on water, it can float due to the phenomenon of surface tension. Surface tension is a property of liquids caused by the cohesive forces between molecules at the surface. Molecules on the surface of the water are pulled towards the bulk of the liquid, creating a "skin" or surface that behaves like an elastic film.
In the case of a horizontally placed needle, the surface tension acts to support the needle. The cohesive forces between water molecules create a slight upward pull on the needle, which helps it float. This happens because the water molecules are more attracted to each other than they are to the steel needle, resulting in a net upward force.
However, when the needle is placed vertically into the water, the situation changes. Now, the needle's weight is acting in the downward direction, creating a downward force that is stronger than the upward force from surface tension. As a result, gravity overcomes the surface tension, causing the needle to sink.
To further understand the concept of surface tension, you can refer to resources like Wikipedia or other relevant online materials that delve deeper into this phenomenon. These resources will provide a more comprehensive explanation of the forces at play and how they affect the behavior of objects on the surface of liquids.