F(g)= Gm1m2/ r^2
If mass is increased, so will the force of gravity because it is in direct relationship with the gravitational force, but if distance is increased, the force of gravity will decrease because it is indirectly related ( since it is on the bottom of the equation)
<h2>
Person must have 8.18 m/s to catch the ball</h2>
Explanation:
Consider the vertical motion of ball
We have equation of motion s = ut + 0.5at²
Initial velocity, u = 12 m/s
Acceleration, a = -9.81 m/s²
Displacement, s = -25 m
Substituting
-25 = 12 x t + 0.5 x -9.81 x t²
4.905 t² -12t - 25 = 0
t = 3.79 sec
Ball hits ground after 3.79 seconds.
So person need to cover 31 m in 3.79 seconds
Consider the horizontal motion of person
We have equation of motion s = ut + 0.5at²
Initial velocity, u = ?
Acceleration, a = 0 m/s²
Displacement, s = 31 m
Time, t = 3.79 seconds
Substituting
31 = u x 3.79 + 0.5 x 0 x 3.71²
u = 8.18 m/s
Person must have 8.18 m/s to catch the ball
No force contributes to density, the density is a physical quantity that is defined as being

the raport between the mass of the object and its volume. However if you want to measure the density of an object you might want to determine its gravity force (weight)

from which knowing the gravitational acceleratin you can find its mass
where

is given in Newtons and

is given in
Question; what causes earthquakes?
Answer; what causes earthquakes are mainly when rocks are underground and then suddenly break along a fault.