Answer:
0.906 N
Explanation:
Formula for magnetic force acting on current carrying cable:

Where I = 345A is the current in the wire, B =
is the magnetic magnitude generated by Earth. L = 46.9 m is the cable length.
is the angle between vector B and cable direction.


Note: I'm not sure what do you mean by "weight 0.05 kg/L". I assume it means the mass per unit of length, so it should be "0.05 kg/m".
Solution:
The fundamental frequency in a standing wave is given by

where L is the length of the string, T the tension and m its mass. If we plug the data of the problem into the equation, we find

The wavelength of the standing wave is instead twice the length of the string:

So the speed of the wave is

And the time the pulse takes to reach the shop is the distance covered divided by the speed:
The average speed would be 33.29m/s.The average speed equation is:

First you will need to solve for the distance you traveled in each scenario. So we can solve this by getting the product of speed and the time traveled.
Scenario 1:
Speed = 29m/s
Time = 120s
Distance = ?
Distance = (29m/s)(120s)
= 3,480m
Scenario 2
Speed = 35m/s
Time = 300s
Distance = ?
Distance = (35m/s)(300s)
= 10,500m
Now that you have the distance of both, you can solve for your average speed.
Answer:
4.25 m/s
Explanation:
They walked the first distance at 5.50 m/s, then the same distance at 3 m/s.
Since the distances are equal, the average speed is simply the average of 5.50 and 3.
(5.50 + 3) / 2 = 4.25
Her average speed over the entire trip is 4.25 m/s.