"the student drops one cannonball, and exactly 1.0 s later drops the other cannonball from the same height. what is the time interval between the first cannonball striking the ground and the second cannonball striking the ground"

Answer;

1 second

Explanation;

Two objects moving at the same speed will always stay the same distance apart. If two objects are moving at different speeds, the distance between them must change.

Therefore; if the distance will be the same and the speed is also the same then the time taken will be the same.

can be answered using momentum.

momentum = p

p1= mass1 * velocity1

p1 = p2

therefore

p1 = 6kg * 4m/s

p1 = 24kgm/s

p2=m2 * v2

24 kgm/s = 7kg * v2

v2 = 24 kgm/s / 7kg

v2= 3.42 m/s

grav forces affect all objects magnetic forces affect magnetic objects and electric currents