Answer:
17.8 kg
Explanation:
The force with which the rock hits the ground is the force of gravity, which is also known as weight of the object, and whose magnitude is given by:
[tex]W=mg[/tex]
where
m is the mass of the object
g is the acceleration of gravity
In this problem, we know the weight of the rock
W = 174 N
We also know the acceleration of gravity,
[tex]g=9.8 m/s^2[/tex]
So, we can find the mass of the rock:
[tex]m=\frac{W}{g}=\frac{174}{9.8}=17.8 kg[/tex]