Which diagram represents an object at static equilibrium?

A

Explanation:

As per the diagram four forces are applied on the box from four different direction.

In first case: F 1 = force exerted by ground in upward direction = 50 N

                    F2 = force due to gravity in downward direction = 50 N

In second case :  F3 = force exerted by player towards right side= 20 N

                            F4 = force due to friction towards left side = 20 N

so if we look at the forces, paired forces are equal and opposite hence they cancel out each other resulting the object to be in same position which means the object is in equilibrium state.

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