Answer:
You now this question state why a person standing at point Y hears an echo
Static friction is the friction that exists between two or more solids that are not moving with a relative speed. To calculate the static friction coefficient we use the formula Fs=us × n where Fs is the static friction , us is the coefficient of static friction and the n is the normal force.
thus the coefficient of static friction will be 5 N÷ 25 N = 0.2
Hence 0.2 is the coefficient of static friction
Answer:
The range of powers is 
Explanation:
From the question we are told that
The far point of the left eye is 
The near point of the left eye is 
The near point with the glasses on is 
From these parameter we can see that with the glass on that for near point the
Object distance would be 
Image distance would be 
To obtain the focal length we would apply the lens formula which is mathematically represented as

substituting values


converting to meters


Generally the power of the lens is mathematically represented as

Substituting values


From these parameter we can see that with the glass on that for far point the
Object distance would be 
Image distance would be 
To obtain the focal length of the lens we would apply the lens formula which is mathematically represented as

substituting values


converting to meters

Generally the power of the lens is mathematically represented as

Substituting values


This implies that the range of powers of the lens in his glass is

The more arms it has the less of a chance the prey has to swim away.