Question 1:
difficultTwo persons are holding a rope of negligible weight tightly at its ends so that it is horizontal. A 15 kg weight is attached to the rope at the mid-point which now no longer remains horizontal. The minimum tension required to completely straighten the rope is:
For Equilibrium condition,
2T cos θ = mg ⇒ T = mg/(2 cos θ)
As, we try to make string horizontal θ approaches 90°. so Tension will become T= mg/2 cos (90°)
i.e  T becomes infinite