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
.
Atoms are a single entity (one type of element) whereas a molecule is a group of 2 or more atoms chemically bonded. Don't be confused that atoms are a single particle because they can be split into protons, neutrons and electrons.
To claculate the gravitational attraction between two bodies with mass 1(m1) and mass 2 (m2) you need to use the equation:
F= G ((m1*m2)/r^2)
Where;
G is the gravitational constant (6.67E-11 m^3 s-2 Kg-1) and
r is the distance between the two objects.
<span>This is best understood with Newtons Third Law of Motion: for every action there is an equal and opposite reaction. That should allow you to see the answer.</span>