For a substance to change from a solid to a liquid, what must happen to its particles? A. They must gain enough kinetic energy to break out of their rigid structure and move independently.
B. They must gain enough kinetic energy to allow them to move freely while still being attracted to one another.
C. They must lose enough of their kinetic energy so that the attractions between them hold in place as they vibrate.
D. They must lose enough of their kinetic energy that their motion is influenced by the attractions between them.

Ray 2 should cross through the focal point on the right side of the lens

Distance covered, s = 8ft - 4ft = 4 ftinitial velocity, u = 34 ft/sthe acrobat is moving upwards and therefore, a = -g = -9.81 m/s^2 = 32.19 ft/s^2applying equation of motion; s = ut -1/2gt^2then,4 = 34t -1/2*32.19t^24 = 34t - 16.095t^2rearranging; -16.095t^2 + 34t - 4 = 0solving the quadratic equation; t = {-34 +/- sqrt [34^2 - 4(-16.)]}/2(-16.095) = 1.06 +/- 0.93 = 0.13 or 1.99the acrobat will take 0.13 seconds to be at 8 ft above the ground. additionally, once at the maximum height, the acrobat will move down and be at the same spot (that is height) after 1.99 seconds moving down.