The $SI$ unit of mechanical equivalent of heat is

Two identical blocks of metal are at $20^{\circ} C$ and $80^{\circ} C$,respectively. The specific heat of the material of the two blocks increases with temperature. Which of the following is true about the final temperature $T_f$ when the two blocks are brought into contact (assuming that no heat is lost to the surroundings)?

$A$ block of ice at $-20\,^oC$ having a mass of $2\,kg$ is added to $3\,kg$ of water at $15\,^oC$. Neglecting heat losses and the heat capacity of the container,what is the final state of the system?

Water of volume $2 \, L$ in a container is heated with a coil of $1 \, kW$ at $27 \, ^\circ C$. The lid of the container is open and energy dissipates at a rate of $160 \, J/s$. In how much time will the temperature rise from $27 \, ^\circ C$ to $77 \, ^\circ C$? [Given: specific heat of water is $4.2 \, kJ/(kg \cdot K)$]

The time required to raise the temperature of $3 \text{ litre}$ of water from $0^{\circ} C$ to $80^{\circ} C$ by a heater operated under $200 \text{ V}$ having resistance of $50 \Omega$ is
[specific heat capacity of water is $4200 \text{ J kg}^{-1} \text{ K}^{-1}$] [density of water $= 1000 \text{ kg/m}^3$] (in $\text{ min}$)

The thermal capacity of a body is $80 \, cal/^{\circ}C$. What is its water equivalent?