Compared with the peak wavelength given off by the Sun, what is the peak wavelength given off by a hotter star?
shorter in wavelength and higher in energy
shorter in wavelength and lower in energy
longer in wavelength and higher in energy
longer in wavelength and lower in energy

Aboxcar traveling at 12 m/s approaches a string of 5 identical boxcars sitting stationary on the track. the moving boxcar collides and links with the stationary cars and they all move off together along the track. what is the final speed of the cars immediately after the collision? (you may take the mass of each boxcar to be 18,537 kg.)

The percent efficiency of a machine can never be 100% (or greater), because in the real world some energy is always converted into a. heat b. work c. input force d. output force

He latent heat of vaporization for ethyl alcohol is 854 j/g. the amount of energy, rounded to the nearest whole number, needed to change 5.20 grams of ethyl alcohol from a liquid to a gas is