A small 3 y. O child comes running towards her father at 2 m/s. The father reaches out and easily grabs her as she hugs his leg. Next, his 9 y. O son comes running at him at the same 2 m/s, but this time the father bends down and brace for impact. Explain how this situation relates to Newton's 1st law,

The illuminance of a surface varies inversely with the square of its distance from the light source. if the illuminance of a surface is 120 lumens per square meter when its distance from a certain light source is 6 meters, by how many meters should the distance of the surface from the source be increased to reduce its illuminance to 30 lumens per square meter?