Because it demonstrates the relationship between a body and the forces acting upon it, and its motion in response to those forces. [Hope that helps]
Answer:
15.8 V
Explanation:
The relationship between capacitance and potential difference across a capacitor is:

where
q is the charge stored on the capacitor
C is the capacitance
V is the potential difference
Here we call C and V the initial capacitance and potential difference across the capacitor, so that the initial charge stored is q.
Later, a dielectric material is inserted between the two plates, so the capacitance changes according to

where k is the dielectric constant of the material. As a result, the potential difference will change (V'). Since the charge stored by the capacitor remains constant,

So we can combine the two equations:

and since we have
V = 71.0 V
k = 4.50
We find the new potential difference:

They can't hear an echo in small room because in it the sound can't be reflected back. For an echo of a sound to be heard,the minimum distance between the source of sound and the walls of the roomshould be 17.2 m. Obviously,in asmall room echoes cannot beheard.
Answer:
Speed at which the ball passes the window’s top = 10.89 m/s
Explanation:
Height of window = 3.3 m
Time took to cover window = 0.27 s
Initial velocity, u = 0m/s
We have equation of motion s = ut + 0.5at²
For the top of window (position A)

For the bottom of window (position B)


We also have

Solving

So after 1.11 seconds ball reaches at top of window,
We have equation of motion v = u + at

Speed at which the ball passes the window’s top = 10.89 m/s