A. Earth crust shakes
Sudden movements in the fault line, ex: San Andreas fault line, can cause sudden earthquakes,
According to Georgia State University, gravitational potential energy<span> is the energy an object possesses because of its position in a gravitational field. This is most commonly in reference to an object near the surface of the Earth, where the gravitational acceleration is assumed to be constant at about 9.8 m/s2.</span>
Answer:



Explanation:
g = Acceleration due to gravity = 
= Angle of slope = 
v = Velocity of child at the bottom of the slide
= Coefficient of kinetic friction
= Coefficient of static friction
h = Height of slope = 1.8 m
The energy balance of the system is given by

The speed of the child at the bottom of the slide is 
Length of the slide is given by


The force energy balance of the system is given by

The coefficient of kinetic friction is
.
For static friction

So, the minimum possible value for the coefficient of static friction is
.