Conservation of Energy:Question 4 If a substance is measured as having a change in heat energy of -100
joules, what does that mean?

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

The sun’s mass is 2.0×10^ 30 kg, its radius is 7.0×10 5 km, and it has a rotational period of approximately 28 days. if the sun should collapse into a white dwarf of radius 3.5×10 3 km, what would its period be if no mass were ejected and a sphere of uniform density can model the sun both before and after?