The harmonic frequency of a musical instrument is the minimum frequency at which a string that is fixed at both ends in the instrument may vibrate. The harmonic frequency is known as the first harmonic. Each subsequent harmonic has a frequency equal to:
n*f, where n is the number of the harmonic and f is the harmonic frequency. Therefore, the harmonic frequency may be calculated using:
f = 100 / 2
f = 50 Hz
Gravity is the force that pulls you down.
(This is kind of a duh! question ... How do we know
which way is "down" ? We feel gravity, and we call
that the "down" direction.)
Magnetic force holds things to fridge doors.
Contact forces need to touch something in order to
exert their force.
Example: Gravity is NOT a contact force.
I don't know about "rubbing things away".
This might be a description of friction, but if so,
it's not a good one.
Buoyant force is what keeps floating things floating.
Air resistance slows things down when they move in air.
Answer:

Explanation:
The amount of work done by Devin when moving the lawn is given by:

where
F is the average force applied
d is the displacement of the lawn
is the angle between the direction of the force and the displacement
Assuming that Devin moves the lawn by applying a force parallel to the displacement, we have:
F = 75 N
d = 1.5 km = 1500 m

Therefore, the work done is

The conditions established by forward- and reverse-bias conditions on a P-N junction diode are: For forwarding bias, the current flows easily without opposition, this causes more current to pass, For reversed bias, the current flow is restricted and this causes less amount of current to pass.
<h3>Meaning of a Forward and reversed bias</h3>
A forward bias is a state attained by a diode as a result of its positive terminal that is connected to the positive part of a circuit and its negative terminal connected to the negative part of the circuit.
A reversed bias is a state attained by a diode as a result of its positive terminal that is connected to the negative part of a circuit and its negative terminal connected to the positive part of the circuit.
In conclusion, The conditions established by forward- and reverse-bias conditions on a P-N junction diode are: For forwarding bias, the current flows easily without opposition, which causes more current to pass, For reversed bias, the current flow is restricted and this causes less amount of current to pass.
Learn more about forward and reversed bias: brainly.com/question/20228400
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