Ahammer is being used to remove a nail from a piece of wood what kind of simple machine is

The graph shows the solubility of several different salts in water, across a range of temperatures. according to the graph, which salt can dissolve at a concentration of about 60 g/100 cm3 of water at 40 degrees celsius?

Amale bird-of-paradise uses a dance to attract mates in which it flaps its tail feathers on the ground and jumps around a potential female mate. a different male bird-of-paradise does a similar dance but it jumps around the female in the opposite direction. the female bird is only attracted to one style of dance, in one direction.

In many humans, exposing the skin to sunlight over prolonged periods of time results in the production of more pigment by the skin cells (tanning). this change in skin color provides evidence that -