If dirt and grease were good conductors of electrical current, then we could make wire
out of dirt and grease instead of expensive copper. Sadly, they're not. So a coating of
dirt and grease on the wire can have a substantial impact on the connection, and can
even block the flow of current across the connection completely. Moreover, in the case
where the ends of the wires are to be soldered, solder does not adhere to dirty wire.
Answer:
μk = 0.26885
Explanation:
Conceptual analysis
We apply Newton's second law:
∑Fx = m*a (Formula 1)
∑F : algebraic sum of the forces in Newton (N)
m : mass in kilograms (kg)
a : acceleration in meters over second square (m/s²)
Data:
a= -0.9 m/s²,
g = 9.81 m/s² : acceleration due to gravity
W= 75 N : Block weight
W= m*g
m = W/g = 75/9.8= 7.65 kg : Block mass
Friction force : Ff
Ff= μk*N
μk: coefficient of kinetic friction
N : Normal force (N)
Problem development
We apply the formula (1)
∑Fy = m*ay , ay=0
N-W-25 = 0
N = 75
+25
N= 100N
∑Fx = m*ax
20-Ff= m*ax
20-μk*100
= 7.65*(-0.90 )
20+7.65*(0.90) = μk*100
μk = ( 20+7.65*(0.90)) / (100)
μk = 0.26885
In short: Electromagnetic radiation is energy that is propagated in the form of electromagnetic waves
Best example of electromagnetic radiation is sunlight. Vsible light of sunlight is only a small portion of the EM spectrum. EM radiation is a form of energy that takes many forms, f.e.: microwaves, radiowaves, etc.
The answer is "Cold Front".
A cold front is characterized as the change zone where a cool air mass is supplanting a hotter air mass. Cold fronts for the most part move from northwest to southeast. The air behind a cold front is recognizably colder and drier than the air in front of it.
Answer:
Explanation:
Magnetic field due to a long current carrying wire can be calculated as follows .
B = 10⁻⁷ x 2I / d where B is magnetic field , I is current .
The wire is along x -axis and the point is on y-axis at a distance of 0.8 m
Magnetic field at point of .8 m on y -axis
B₁ = 10⁻⁷ x 2 x 39 / 0.8
= 97.5 x 10⁻⁷ T .
Second wire is parallel to z-axis and passes through point on y-axis at a distance of 4.4 m . So the given point is at a distance of 4.4 - .8 = 3.6 m
Magnetic field
B₂ = 10⁻⁷ x 2 x 47 / 3.6
= 26.11 x 10⁻⁷ T .
Both these magnetic fields are perpendicular to each other so
Resultant magnetic field
B = √ ( 26.11² + 97.5² ) x 10⁻⁷ T
= √( 681.73 + 9506.25 ) x 10⁻⁷ T
= √( 10187.98) x 10⁻⁷ T
= 100.93 x 10⁻⁷ T .