What is the twisted ladder shape of the DNA called?

If 21.2 kcals of energy is released by this reaction, how many kj does the reaction release? (1 cal 4.184 j)

Emmy kicks a soccer ball up at an angle of 45° over a level field. she watches the ball's trajectory and notices that it lands, two seconds after being kicked, about 20 m away to the north. assume that air resistance is negligible, and plot the horizontal and vertical components of the ball's velocity as a function of time. consider only the time that the ball is in the air, after being kicked but before landing. take "north" and "up" as the positive ‑ and ‑directions, respectively, and use ≈10 m/s2 for the downward acceleration due to gravity.

Auniform brick of length 25 m is placed overthe edge of a horizontal surface with a maximum overhang of 12.5 m attained withouttipping. now two identical uniform bricks of length25 m are stacked over the edge of a horizontalsurface. what maximum overhang is possible forthe two bricks (without tipping)? answer in units of m.