** asap ! **
how can astronomers determine a star’s chemical composition?
a. by looking at its temperature
b. by using a spectrograph
c. by comparing its size to the sun
d. by comparing its color to the sun

Much of the information taught in earth-space science would not be available if it weren’t for our remote sensing abilities. explain two ways our remote sensing strategies contribute to our knowledge of these topics.

Why is the energy that results from a roller coaster's position at the top of a hill referred to as potential energy?

An insulated thermos contains 148 g of water at 72.7 ˚c. you put in a 11.7 g ice cube at 0.00 ˚c to form a system of ice + original water. the specific heat of liquid water is 4190 j/kg•k; and the heat of fusion of water is 333 kj/kg. what is the net entropy change of the system from then until the system reaches the final (equilibrium) temperature?