<h3>Explanation</h3>
,
where
is the current;
is the drift speed;
is the cross-section area of the wire, 
is the number of charge carrier per unit volume, and
is the charge on each charge carrier.
Area of a circular cross-section:
,
where
is the radius of the wire.
and are the same for all four samples, for they are made out of the same material.
As a result, of each wire is directly proportional to 
where the value of 
is constant.
For each of the four wires:
.
How do the four wires rank by their current?
d > a > b > c.
Answer:
2. The metal surface exerts less frictional force because there are fewer bumps and irregularities on it than there are on the concrete.
Explanation:
Frictional force is a force that is exerted between two surfaces in contact with each other. Frictional force always opposes the direction of relative motion of the two surfaces: for instance, for a ball moving along a surface, the force of friction exerted by the surface on the ball points opposite to the direction of motion of the ball.
The magnitude of the frictional force for a ball moving on a flat surface is given by
where
is the coefficient of friction
m is the mass of the ball
g is the acceleration of gravity
The value of depends on the type of surface involved. In particular, a smooth surface has a smaller value of , while a rough surface will have a bigger value. In this case, we are comparing a smooth metal surface with concrete: since the metal surface has fewer bumps and irregularities than concrete, it has a smaller value of coefficient of friction, so it exerts less frictional force than concrete.
Answer:
D. 66.4
Explanation:
So this problem uses SOHCAHTOA or the three trig functions.
Specifically this uses cosine, because it has an adjacent and a hypotenuse.
First you would determine what to do on the calculator, and since the problem is saying so, use the inverse cosine button. This will give you a angle measure from the decimal.
On a calculator, type in cos^-1(6/15). I used 6/15 because cosine is adjacent over hypotenuse. This will give you 66.4, which is D on the answers.
<span>P = energy/t = 0.0025/1E-8 = 250000 W
I(ave) = P/A = 250000/(pi*0.425E-3^2) = 4.4056732E11 W/m^2
I(peak) = 2I(ave) = 8.8113463E11 W/m^2
Electric field E = sqrt(I(peak)*Z0) = 1.8219499E7 V/m, where
free-space impedance Z0 = sqrt(µ0/e0) = 376.73031 ohms</span>
Answer:
the speed of the cruiser relative to the pursuit ship is 0.3846c
Explanation:
the solution is in the attached Word file
