PLEASE help me with these questions as soon as possible i need to turn it in!!!!
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The text does not specify whether the resistance R of the wire must be kept the same or not: here I assume R must be kept the same.
The relationship between the resistance and the resistivity of a wire is
where
is the resistivity
A is the cross-sectional area
R is the resistance
L is the wire length
the cross-sectional area is given by
where r is the radius of the wire. Substituting in the previous equation ,we find
For the new wire, the length L is kept the same (L'=L) while the radius is doubled (r'=2r), so the new resistivity is
Therefore, the new resistivity must be 4 times the original one.
The relationship between the resistance and the resistivity of a wire is
where
A is the cross-sectional area
R is the resistance
L is the wire length
the cross-sectional area is given by
where r is the radius of the wire. Substituting in the previous equation ,we find
For the new wire, the length L is kept the same (L'=L) while the radius is doubled (r'=2r), so the new resistivity is
Therefore, the new resistivity must be 4 times the original one.
Answer:
Part a)
Part b)
Part c)
Part d)
Explanation:
Part a)
While bucket is falling downwards we have force equation of the bucket given as
for uniform cylinder we will have
so we have
now we have
now we have
Part b)
speed of the bucket can be found using kinematics
so we have
Part c)
now in order to find the time of fall we can use another equation
Part d)
as we know that cylinder is at rest and not moving downwards
so here we can use force balance