A. 1/9
Explanation:
The gravitational force between two objects is given by

where
G is the gravitational constant
m1 and m2 are the two masses
r is the distance between the two masses
From the formula, we see that the magnitude of the force is inversely proportional to the square of the distance: therefore, if the distance is tripled (increased by a factor 3), the magnitude of the force changes by a factor

Complete Question
Question 18 (3 points) Solve the problem. (3 points) A solar reflector is made using 31 identical triangular-shaped mirrors, each having sides 2.4m, 2. 3m, 1.5 m. What is the total surface area of the reflector?
A) 33 m2
B) 86 m2
C) 52 m2
D) 34 m2
Answer:
The value is 
Explanation:
From the question we are told that
The sides are a = 2.4 m
b = 2.3 m
c = 1.5 m
Generally the semi perimeter is mathematically represented as

=> 
=> 
Generally the using Heron's formula we have that the surface are a is mathematically represented as

=> 
=> 
Explanation:
It is given that the number of electrons passing through the cross-sectional area in 1 s is
. Also, we know that charge on an electron is
, then negative charge crossing to the left per second is as follows.
I- =
I- = 0.544 A
As it is given that the number of protons crossing per second is
, as the charge on the proton is
, then positive charge crossing to the right per second is calculated as follows.
I+ =
I+ = 0.224 A
I = l I+ l + l I- l
So, I = 0.544 + 0.224
= 0.768 A
Thus, we can conclude that the current in given hydrogen discharge tube is 0.768 A.
Copper will still be a solid at room temperature
Here is the link for the info: http://education.jlab.org/itselemental/ele029.html