Explanation:

When a cable is suspended between two supports and subjected to uniformly distributed load, it experiences tension throughout its length. The tension is maximum at its mid-span and decreases towards the supports. When the temperature suddenly drops, the cable contracts due to thermal contraction and its length reduces. This leads to a change in the tension in the cable.

Effect on Cable Tension:

The effect of temperature change on cable tension depends on the coefficient of thermal expansion of the cable material and the supports. If the coefficient of thermal expansion of the cable is greater than that of the supports, then the cable will contract more than the supports and the tension in the cable will decrease. Conversely, if the coefficient of thermal expansion of the supports is greater than that of the cable, then the tension in the cable will increase.

In most cases, the coefficient of thermal expansion of the cable is greater than that of the supports. Therefore, when the temperature suddenly drops, the cable contracts more than the supports and the tension in the cable decreases. The maximum tension in the cable occurs at mid-span and this tension reduces due to thermal contraction of the cable.

Effect on Cable Sag:

The sag in the cable also changes due to thermal contraction. When the temperature drops, the cable contracts and its length reduces. This leads to an increase in the cable tension which reduces the sag in the cable. If the temperature drop is significant, the cable may become taut and lose its catenary shape.

Conclusion:

In conclusion, when the temperature in a cable suddenly drops, the maximum tension in the cable decreases due to thermal contraction of the cable. The sag in the cable also decreases due to the increase in tension. It is important to consider the effect of temperature change on cable tension and sag while designing cable structures.