You're conducting a physics experiment on another planet. you drop a rock from a height of 2.1 m and it hits the ground 0.6 seconds later. what is the acceleration due to gravity on this planet?
a. 7.0 m/s2
b. 9.8 m/s2
c. 11.7 m/s2
d. 5.2 m/s2
(what formula should i use to solve this on my own? )

The formula to use is the one that connects the acceleration,
the distance fallen, and the time spent falling:

         Distance = 1/2 a T² .

You said  2.1 meters in 0.6 second .

                                                         2.1 m              = 1/2 a  (0.6 sec)²

Multiply each side by  2 :                  4.2 m              =       a (0.6 sec)²

Divide each side by (0.6 sec)² =     (4.2/0.36) m/s² =        a

                                                         a = (11 and 2/3) m/s²

                                        (about 19% more than Earth's gravity)

Aform of energy that is reflected or emitted from objects in the form of electrical and magnetic waves that can travel through space. there are many forms of  electromagnetic  energy including gamma rays, x rays, ultraviolet radiation, visible light, infrared radiation, microwaves and radio waves.

The answer is orbit around nucleus