A three tiered birthday cake rests on a table. From bottom to top, the cake tiers weigh 17N, 12N, and 7N, respectively. What is the magnitude and direction of the normal force acting on the second tier?

The magnitude of the poynting vector of a planar electromagnetic wave has an average value of 0.939 w/m^2 . the wave is incident upon a rectangular area, 1.5 m by 2.0 m, at right angles. how much total electromagnetic energy falls on the area during 1.0 minute?