The sun is a natural resource used by people. Why is the sun considered a renewable resource? * the sun goes away at night and then comes back in the morning
on cloudy days, the sun cannot be used
solar energy from the sun is limited
the sun is an unlimited source of energy that isn't used up as fast as people use it

Aneuron is stimulated with an electric pulse. the action potential is detected at a point 3.70 cm down the axon 0.0052 s later.when the action potential is detected 7.20 cm from the point of stimulation, the time required is 0.0063 s. what is the speed of the electric pulse along the axon? (why are two measurements needed instead of only one? )

Sediment layers stop lateral spreading when: they encounter a barrier they encounter an opposing current they run out of additional sedimentary material

Archaebacteria use for movement. celia flagella pili cell walls