Answer:
665 ft
Explanation:
Let d be the distance from the person to the monument. Note that d is perpendicular to the monument and would make 2 triangles with the monuments, 1 up and 1 down.
The side length of the up right-triangle knowing the other side is d and the angle of elevation is 13 degrees is

Similarly, the side length of the down right-triangle knowing the other side is d and the angle of depression is 4 degrees

Since the 2 sides length above make up the 200 foot monument, their total length is
0.231d + 0.07d = 200
0.301 d = 200
d = 200 / 0.301 = 665 ft
E = mass x gravity x height
This is false. they flow west to east
Answer:
2.7067 eV
Explanation:
h = Planck's constant = 
c = Speed of light = 
= Threshold wavelength = 459 nm
Work function is given by

Converting to eV


The work function W0 of this metal is 2.7067 eV
Answer:
Let No be initial no of atoms
N = N0 / 2 after 1 half-life
N = N0 / 4 after 2 half-lives
So after 2 half-lives 20 of the 80 atoms remain