Which is the source of variations in a populations of organisms

When do vernal equinoxes usually occur? autumnal? Also, explain the difference between neap tides and spring tides.

What percentage of the intensity gets through both polarizers?

The bottom sphere is briefly touched by another conducting sphere of the same size, mounted on an insulating handle. Assuming that the charge of the bottom sphere is q before it is touched by the other sphere, what is its charge after it is touched?

What is earth made of

Is momentum conserved in the collision?

an athlete whirls a 7.00 kg hammer tied to the end of a 1.3 m chain in a horizontal circle the hammer moves at the rate of 1.0 rev/s what is the centripetal acceleration of the hammer

Relaying a message from a membrane receptor to a molecule that performs a specific function within a cell occurs when

Ultrasound consists of sound at frequencies most people can hear?

Ali has less mass flying in a jet high above the earth than when she stands on the surface of the earth. True False

A passenger jet flies from one airport to another 1,333 miles away in 2.2 h. Find its average speed in the mks system of units.