Answer:
(a)
(b) 
Explanation:
Part (a)
The total length of copper cord L=86.3 m
The cross sectional area A=1.71×10⁻⁶m²
The resistivity of copper p=1.72×10⁻⁸Ω
Thus the resistance of extension cord is

Part (b)
The resistance of trimmer Rt=17.9 ohms
When voltage of 120V is applied then the current I is passing through series circuit is

Thus the voltage across the trimmer is:

Human error (average human reaction time is .2 seconds)
Answer:

Explanation:
Given that
, we use Kirchhoff's 2nd Law to determine the sum of voltage drop as:

#To find the particular solution:

Hence the charge at any time, t is 
there will no resultant force
Explanation:
this is because if the forces are balanced on opposite direction. then they cancel each other out
5 newton's ---------> <--------- 5 newton's
then both forces will cancel each other out as a result there is no resultant force and the newton's laws states that if there is no resultant the object will continue in its state of rest (remains there) or it will in continue in its uniform motion in a straight line.
I hope you understand,
Answer:
Amplitude is decreased by a factor of
if intensity is decreased by a factor of 3.
Explanation:
Intensity of a sound wave is directly proportional to the square of its amplitude.
Therefore, if intensity is
and amplitude is
, then
, where,
is constant of proportionality.
Now, if intensity of sound wave is decreased by a factor of 3. So,
New intensity is, 

Plug in
for
. This gives,

Therefore, amplitude is decreased by a factor of
.