Faina says that an object cannot be in mechanical equilibrium when only a single force acts on it. do you agree or disagree? explain.

A single force can't bring mechanical equilibrium. As the third law of Newton which very fresh and deliberately worded: To each action, there is dependably an equivalent and inverse response. The third law implies by action, the force. So the forces exist in pairs. Besides, by equilibrium, we mean either the body is rest or in uniform movement (both transnational or rotational) because of no external force or net external force is zero by the first law of motion. Thus no mechanical equilibrium condition is acquired by one single force.

Hence, I agree with Faina statement.

graph slopes whilst gas cools, then it is flat whilst conensation to liquid happens, the coolong liquid then graphs as a slope when it solidifies graph is flat

latent heat