Answer:
The <em>net gravitational force it exerts</em> is 
Explanation:
Newton's Law of Gravitation can be written as

where <em>G is the Gravitational Constant, m1 and m2 are the masses of two objects, and r is the distance between them</em>. In this case, the spheres are loacted in straight line, so instead of a vector r, we have a distance x in meters. The distances and masses are given in the problem, and the smaller sphere is between the other two spheres. This means <u>the sphere 1 is in the middle, the sphere 2 is on the left of 1, and the sphere 3 is on the right of 1</u>, so
is the force that 2 feels because of 1, and
is the force that 3 feels because of 1.
<em>If we replace the data in those previous equations</em>, we have that


Finally, adding both results, the net force the sphere 1 exerts is

Explanation:
We use the Theorem of conservation of mechanical energy for finding the velocity when it strikes the ground:
Ei = Ef
Ki + Ui = Kf + Uf
Ui = Kf
m g h = 1/2 m v^2
v = sqrt(2gh)
So the momentum will be:
p = mv = m * sqrt(2gh)
Answer: conduction
Explanation:
Because you are physically touching the handle
I think the answer is Helium.
Please tell me if I'm wrong.