Is there a net force?

No!

I have no clue

Yes!

There is NO net force acting on the hanging weight. The net force is ZERO.

Explanation:

If the object (the weight) is NOT moving, and in static equilibrium hanging from the support, that means that the net force on it is ZERO. There are two forces acting, one is that due to gravity and the other one the tension of the string, Both of these forces must be equal in magnitude but pointing in different directions, so they cancel each other.

.) the observation by semmelweis that more mothers died of childbed fever when their doctors also worked in the morgue

force is based upon mass and acceleration.the statement is not always true.

it can be explained from newton's second law of motion.

as per newton's second law of motion the rate of change of momentum is directly proportional to the applied force and takes place along the direction of force.

mathematically it can be written as -

                                              ⇒      

here   k is the proportionality constant whose value is 1.

                                                            [a is the acceleration=dv/dt]

hence we see that force not only depends on mass and acceleration but also on velocity and rate of change of mass. force f will depend on mass and acceleration only when mass is constant.

hence the statement that force is based upon mass and acceleration is false.