Thanks to Einstein's equation E = mc² we now know that energy is equivalent to what?

In a heat of an engine, if 700 j enters the system, and the piston does 400 j of work what is the final internal (thermal) energy of the system if the initial energy is 1,500 j

[ou.03jthe pictures below show the wavelengths and intensities of electromagnetic radiations emitted by three stars, star 1, star 2, and star 3. intensity intensity- intensity- 1000 3500 6000 8500 11000 wavelength (a) star 1 1000 3500 6000 8500 11000 1000 3500 6000 8500 11000 wavelength (a) wavelength (a) star 2 star 3 which of these statements is correct about the color of the three stars? star 2 is white in color o star 2 is yellow in color star 1 and star 3 are yellow in color star 1 and star 3 are white in color

You dissolve 8.65 grams of lead(l) nitrate in water and then you add 2 50 grams of aluminum. this reaction occurs 2ai(s)+ 3pb(no3)2(aq) -3pb(s)+ 2aino3la(aq) the theoretical yield of solid lead?