You're conducting a physics experiment on another planet. you drop a rock from a height of 2.3 m and it hits the ground 1.1 seconds later. what is the acceleration due to gravity on this planet?
a. 4.2 m/s2
b. 3.8 m/s2
c. 2.4 m/s2
d. 9.8 m/s2

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?