How do humans contribute to eutrophication in both of these cases?
● farms:
● lawns:

The main factor is the present that causes eutrophication is the humans and their activities. The activities on the farms and the laws are just some of the numerous examples where the humans manage to cause eutrophication.

The farms can be either planet with crops or places where animals are kept and raised. If there's crops planted, than the humans use a lot of fertilizers. The fertilizers have mostly high concentrations of nitrogen, potassium, and phosphorus. Big portion of them end up in the groundwater and or the streams, rivers, and other water bodies. If there's animals on the farm, the waste from the animals ends up in the water bodies. Those two things manage to significantly increase the nutrients in the waters and cause eutrophication of it.

The lawns also require some fertilizers, and in the same manner as in the farms they often end up in the water bodies. Also, when the lawns are cut, the grass that has been cut usually finds its way in the water bodies, thus resulting in increased nutrition of the water bodies, thus eutrophication.

Friction is a force that acts against a moving object to slow it down. A type of friction is air resistance. Friction opposes the direction in which the object is moving, causing the object to decrease in speed, or stop all together.