A water strider (which can walk on water)has legs that are coated with a hydrophobic substance. What might be the benefit? What would happen if the substance were hydrophilic?

The water striders are the species, which are about half an inch in length and exhibiting a thin body with three legs set. The legs of water striders exhibit small hairs, which helps in repelling water and holding air. The water striders by repelling water stand on the surface of the water and the captivated air permit them to float and move readily.  

The legs of water striders are coated with hydrophobic substances, which helps in repelling water and assists in keeping the terminals of the legs from getting coated with water. In case, if the legs of the species were coated with a hydrophilic substance, then water would be drawn up by the legs and would make the striders break through the surface and thus would have a tough time to walk on water.  

relative dating involves things like higher layers are most recent than rocks lower in the sequence. this can be extended to the known sequence of fossils. rocks containing rabbit fossils are later than those containing dinosaur fossils.  

absolute dating methods mainly use radioactive elements that have known rates of decay and produce recognizable products. for example potassium 40 decays to produce argon. once a rock has solidified the argon is trapped. by measuring the argon and potassium0 you can get an accurate number for the age.  

some other methods are good for archaeological ages. dendrochronology involves recognizing the sequence of tree rings. the orientation of magnetized particles in baked clay can be used to date a fire.

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