The resistance of the piece of wire is

where

is the resistivity of the copper

is the length of the piece of wire

is the cross sectional area of the wire
By substituting these values, we find the value of R:

Then, by using Ohm's law, we find the potential difference between the two points of the wire:
Answer:

Explanation:
= Change in frequency = 2.1 Hz
= Frequency of source of sound = 440 Hz
= Maximum of the microphone
= Speed of sound = 343 m/s
= Time period = 2 s
We have the relation

Amplitude is given by

The amplitude of the simple harmonic motion is
.
Answer:
The average velocity is 0.15 m/s
Explanation:
Use the definition of average velocity as the distance traveled divided the time it took.
Since the movement was on the plane from the origin (0, 0) to the point (-30, 20) corresponding to 30 m west and 20 m north, we calculate the distance using the distance between two points on the plane:

Then the magnitude of the average velocity can be estimated via the quotient between distance divided time, but since the units required are meters per second, we first convert the four minute time into seconds: 4 * 60 = 240 seconds.
Then the average velocity becomes:

Answer:
U = 11.67 W/m² °C
Explanation:
Inner diameter, d = 2.5 cm = 0.025 m
Thickness of the wall, t = 2 mm = 0.002 m
thus, the outer diameter, D = d + 2t = 0.025 + 2 x 0.002 = 0.029 m


Now, based on outside convection heat transfer
we have

on rearranging, we get

where,
are the perimeter respective to inner and and outer diameter
on substituting the values, we get

or
U = 11.67 W/m² °C