Answer:
(a)
(b)
Explanation:
The angular speed is a measure of the rotation speed. Thus, It is defined as the angle rotated by a unit of time:
The arc length in a circle is given by:
s is the length of an arc of the circle, so .
Replacing (2) in (1):
a) Now, we calculate the angular speed:
b) We use (1) to calculate the time it takes to make one revolution, which means that is
.
Answer:
Explanation:
The resistance of a wire is given by:
where
is the resistivity of the material
L is the length of the wire
A is the cross-sectional area of the wire
1) The first wire has length L and cross-sectional area A. So, its resistance is:
2) The second wire has length twice the first one: 2L, and same thickness, A. So its resistance is
3) The third wire has length L (as the first one), but twice cross sectional area, 2A. So, its resistance is
By comparing the three expressions, we find
So, this is the ranking of the wire from most current (least resistance) to least current (most resistance).