Answer:
400 N
Explanation:
By the law of friction,
is the maximum frictional force, 
is the coefficient of friction and 
is the reaction on the refrigerator. On a horizontal surface, the reaction is equal to the weight of the refrigerator.
While not moving, the fricition on the refrigerator is static friction. So, 
This is the maximum frictional force and is more than the applied horizontal force of 400 N. Frictional force cannot be more than the applied force, else it would actually pull the refrigerator backwards (a strange thing, if it were to happen). It is equal to the extent of the applied force because the applied force is not enough to overcome the maximum.
Hence the frictional force is 400 N.
PS: Note that we do not use the coefficient of kinetic friction because applied force could not overcome the static friction.
Answer:
Current = 8696 A
Fraction of power lost = 
= 0.151
Explanation:
Electric power is given by
where I is the current and V is the voltage.
Using values from the question,
The power loss is given by
where R is the resistance of the wire. From the question, the wire has a resistance of 
per km. Since resistance is proportional to length, the resistance of the wire is
Hence,
The fraction lost = 
Answer:
The climate of the earth throughout history has always been <em><u>fluctuated between hot and cold periods. </u></em>
Answer:
The normal resting heart rate for adults over the age of 10 years, including older adults, is between 60 and 100 beats per minute (bpm). Highly trained athletes may have a resting heart rate below 60 bpm, sometimes reaching 40 bpm. The resting heart rate can vary within this normal range.
Explanation:
I hope that answers your question!
A free electron is one which has become detached from a covalent bond between two atoms and is able to move around from atom to atom and possibly take part in electric current flow.
