gravity is a force between any two objects with mass. why doesn't a person feel a gravitational force between him/herself and another person?
a) a person doesn't exert a gravitational force.
b) the two gravitational forces cancel each other out.
c) the gravitational forces of people is so small it is overshadowed by that of earth.
d) there are so many people we are actually balanced by all the different gravitational forces.

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