physics
posted by pop on .
A light string has its ends tied to two walls separated by a distance equal to fiveeighths the length of the string. A 53 kg mass is suspended from the center of the string, applying a tension in the string.
What is the tension in the two strings of length L/2 tied to the wall? The acceleration of gravity is 9.8 m/s^2.
Answer in units of N.

Draw the triangles.
half the weight is supported by each side.
Let theta be the angle from the wall horizontal to the string. Then on each side, SinTheta=Weight/(2*tension)
But tan cosTheta= half wall distance/halfstring distance
costheta= 5/8
But sin^2theta+cos^2theta=1
or weight^2/4Tension^2+25/64=1
solve for tension.