A telephone lineman is told to stretch the wire between two poles so the poles exert an 800N force on the wire. As the lineman does not have a scale to measure forces, he decides to measure the speed of a pulse created in the wire when he hits it with a wrench. The pulse travels 60m from one pole to the other and back again in 2.6s. The 60m wire has a mass of 15kg.

Should the wire be tightened or loosened?

A. Loosened
B. Tightened

f = 532.46 N

Explanation:

V = √(f / u) is the formula that describe the relationship between the speed of a pulse moving on a rope, and the force being exerted on the rope.

u = m / L, such that

u = 15 / 60

u = 0.25 kg/m

We calculate the speed of the pulse

v = distance / time

v = (2 * 60) / 2.6

v = 46.15 m/s

v = √(f / u)

F = uv²,

F = 0.25 * 46.15 * 46.15

F = 532.56 N

The rope should be tightened because the force in the wire is less than the required force.

the current is 0.6

voltage ÷ resistance = current

so 12 ÷ 20 = 0.6

molecules are free to separate from each other and will take on the shape of the container. molecules move completely at random and high speeds. they vibrate in a fixed position and do not move around much. molecules expand to the edge of their container.