Answer:
11.27N
Explanation:
Given parameters:
Mass of the book = 1.15kg
Unknown:
Magnitude of the normal force = ?
Solution:
The normal force is the vertical force exerted by a body on an object.
It can be described as the weight of an object.
Normal force = mass x acceleration due to gravity
Normal force = 1.15 x 9.8 = 11.27N
People have diffrent body builds and bone structure
A beat is an interference pattern between two sounds of slightly different frequencies, perceived as a periodic variation in volume whose rate is the difference of the two frequencies. Frequency beat is equal to,

The reference frequency in our case would be 392Hz, and since there is the possibility of the upper and lower range for the amount of beats per second that the two possible frequencies are heard would be


Therefore the two possible frequencies the piano wire is vibrating at, would be 396Hz and 388Hz
Gravitational force = G ( m1 m2 ) / r²
3 = G ( m1 m2 ) / ( 10 )²x = G ( m1 m2 ) / ( 5 )²We shall divide those two equations:3 / x = 1/100 / 1/25 = 25 / 100 = 1 / 4x · 1 = 3 · 4x = 12Answer:C. 12 N