From the concept of optics on a curvature of a spherical mirror, the proportion for which the focal length is equivalent to half the radius of curvature is fulfilled. Mathematically this is

Here,
f = Focal Length
R = Radius
Rearranging to find the radius we have,

Replacing with our values,
R = 2(13.8cm)
R = 27.6cm
Therefore the radius of the spherical surface from which the mirror was made is 27.6cm
This is unclear. What are the objects? Is it a balloon? A rubber ball?
Answer:
exposing it to a flame to see if it catches on fire
Explanation:
A chemical property is when the matter changes into a different substance. This is true when you expose it to a flame because if a substance is burned, it will change into a new substance. All the other options are examples of physical changes.
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Hope this helps!
It’s half the mass of the object by its velocity ^2
Answer:
Bile helps in the digestion of fats