If the specific heat of water is 4.18 J/g⁰C and the specific heat of a rock is 0.418 J/g⁰C, how many grams of rocks at 200⁰C must be added to 100 grams of water to raise the water temperature from 20⁰C to 80⁰C? (Hint: the heat energy gained by water is equal to the heat energy lost by the rocks and both water and rocks have the same final temperature.) (Do not include units, round to the nearest whole number)

The ozone molecule o3 has a permanent dipole moment of 1.8×10−30 cm. although the molecule is very slightly bent-which is why it has a dipole moment-it can be modeled as a uniform rod of length 2.5×10−10 m with the dipole moment perpendicular to the axis of the rod. suppose an ozone molecule is in a 8000 n/c uniform electric field. in equilibrium, the dipole moment is aligned with the electric field. but if the molecule is rotated by a small angle and released, it will oscillate back and forth in simple harmonic motion.what is the frequency f of oscillation?