A4.9-n hammer head is stopped from an initial downward velocity of 3.2 m/s in a distance of 0.45 cm by a nail in a pine board. in addition to its weight, there is a 15 n downward force on the hammer head applied by the person using the hammer. assume that the acceleration of the hammer head is constant while it is in contact with the nail and moving downward. (a) calculate the downward force f~ exerted by the hammer head on the nail while the hammer head is in contact with the nail and moving downward. (b) suppose the nail is in hardwood and the distance the hammer head travels in coming to rest is only 0.12 cm. the downward forces on the hammer head are the same as on part (a). what then is the force f~ exerted by the hammer head on the nail while the hammer head is in contact with the nail and moving downward

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