D = 40.5 g / 15.0 mL<span>d = 2.70 g/mL</span>
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.
Answer:
Explanation:
A )
speed of swimming in still water is given by the expression
distance / time
= 50 / 25
= 2 m /s
In lane 1 , 1.2 cm/s current is flowing in the direction that the swimmers are going so swimmers will cover distance at the rate of 2 + 1.2 = 3.2 m /s.
time to cover distance of 50 m in lane 1
= distance / speed
= 50 / 3.2 = 15.625 s
In lane 8 , 1.2 cm/s current is flowing against the direction that the swimmers are going so swimmers will cover distance at the rate of 2 - 1.2 = .8 m /s.
time to cover distance of 50 m in lane 1
= distance / speed
= 50 / .8 = 62.5 s
The answer is A
Explanation:
Vacuuming doesn’t involve a lot of physical movements.
Answer:
147.7 N
221.55 Nm
Explanation:
P = Pressure = 100000 Pa
= Mass-specific gas constant = 287.015 J/kg k
T = Temperature = 10+273 = 283 K
C = Drag coefficient = 1.1
A = Area
r = Radius = 0.2 m
v = Speed of wind = 
L = Length of pole
Density

Drag force

Force on the circular sign is 147.7 N

Bending moment at the bottom of the pole is 221.55 Nm