Answer: 0.258
Explanation:
The resistance
of a wire is calculated by the following formula:
(1)
Where:
is the resistivity of the material the wire is made of. For aluminium is
and for copper is 
is the length of the wire, which in the case of aluminium is
, and in the case of copper is 
is the transversal area of the wire. In this case is a circumference for both wires, so we will use the formula of the area of the circumference:
(2) Where
is the diameter of the circumference.
For aluminium wire the diameter is
and for copper is 
So, in this problem we have two transversal areas:
<u>For aluminium:</u>

(3)
<u>For copper:</u>

(4)
Now we have to calculate the resistance for each wire:
<u>Aluminium wire:</u>
(5)
(6) Resistance of aluminium wire
<u>Copper wire:</u>
(6)
(7) Resistance of copper wire
At this point we are able to calculate the ratio of the resistance of both wires:
(8)
(9)
Finally:
This is the ratio
The average walking speed for an adult would be around 6 m/s, and average leght of adult human legs is around 1m so the best answer of the given answers would be 7.9 m/s
Answer:
True
Explanation:
If we swing a bucket of water fast enough in a vertical circle the water does not spill out even at the top-most position of the bucket. This happens because the centrifugal force acting away from the center in a circular motion neutralizes or overcomes the gravitational force on the water particles.
<u>Centrifugal force is mathematically related as:</u>

where:
m = mass of the revolving body
r = radius of revolution
angular velocity in radians per second
This force F acts in radially outward direction.
Answer:

Explanation:
Our values are


We can find the time through



The expression for the distance between the Earth and the spaceship is as follow:

Where c is Light speed, and t our previous time.


Therefore the distance between the Eath and the Spaceship is
m