20. Small block A sits on top of large block B, as shown in the diagram. Both blocks are being pulled to the right along a flat surface by a horizontal pull of 100 N, as shown in the figure. Both blocks are moving together at a constant velocity of 2.0 m/s to the right, and both have the same weight. Which free-body
diagram shows the horizontal forces acting on the upper block. A?
B
100N poll
WOM
w

1. what is the relationship between wavelength and the penetrating power of an electromagnetic wave? a) the penetrating power has no relationship to the wavelength. b) the penetrating power increases as the wavelength increases. c) the penetrating power decreases as the wavelength increases. d) the penetrating power decreases as the wavelength decreases. 2. as ice melts and turns into water, the speed of sound through the material would most likely do what? justify your answer. a) the speed would not change because the material is always water. b) the speed of sound would increase because the density of water is less than that of ice. c) the speed of sound would increase because energy is added to ice in order to make it melt. d) the speed of sound would decrease because sound travels faster through solids than liquids. 3.which of these waves need a medium to travel through? a) sound b) x-rays c) infrared rays d) visible light