When an object is placed 8 millimeters from a concave spherical mirror, a clear image can be projected on a screen 16 millimeters in front of the mirror. if the object has a height of 4 millimeters, the height of the image is
a. 2 millimeters.
b. 4 millimeters.
c. 8 millimeters.
d. 12 millimeters.

The question can be answered by ratio and proportion by similar triangles u/v=Hi/Ho

8 : 16 = x : 4
8 / 16 = x / 4
16x = 32
x = 2

So the correct answer is letter A. 2 millimeters. 

Jet streams are relatively narrow bands of strong wind in the upper levels of the atmosphere. the winds blow from west to east in jet streams but the flow often shifts to the north and south. jet streams follow the boundaries between hot and cold air. the earth's rotation is responsible for the jet stream as well.