Answer to Question #156887 in Electric Circuits for sheena sheen

Question

A framed painting weighs 30kg. The two wires supporting it makes an angle of 120° with

each other. What are the tensions in the wire?

Answer 1

Let's solve this problem :

In order to stop the traffic light from accelerating down, an equal but opposite resultant force needs to be applied. Each wire supports the light’s weight equally. The resultant force splits the 120 degree angle in half. Two 90 degree triangles are formed between the resultant force and the horizontal. Giving two 30 - 60 - 90 triangles.

The triangles need to have a combined force along the resultant that is equal and opposite to the weight of the light

The tension in the ropes is found dividing the adjacent side of the angle (150 N) by the cos 60˚

T = (150N)/(cos 60˚) T = 3000N The tension is the same magnitude for each rope, but their x components are opposite each other, giving rope 1 a negative vector, and rope 2 a positive vector.

T(rope 1) = -300N

T(rope 2) = 300N