For the given circuit of p-n junction diode which is correct

Consider two rods of same length and different specific heats (S₁, S₂), conductivities (K₁, K₂) and area of cross-sections (A₁, A₂) and both having temperatures T₁ and T₂ at their ends. If rate of loss of heat due to conduction is equal, then

An object of mass 3 kg is at rest. Now a force of $$\overrightarrow F $$ = 6t² $$\widehat i$$ + 4t $$\widehat j$$ is applied on the object then velocity of object at t = 3 sec. is

A lift of mass 1000 kg which is moving with acceleration of 1 m/s² in upward direction, then the tension developed in string which is connected to lift is