70 kg man walks out on a 10 kg beam that rests on, but is not attached to, two supports. When the beam just starts to tip, what is the force exerted on the beam by the right support

The force is  

Explanation:

From the question we are told that

      The mass of the man is  

      The mass of the beam is

Now from the question we can deduce that when this beam start to tip that both the force exerted by the weight of the man and that of the beam is been supported by the  right support so

 The force exerted on the right support is mathematically evaluated as

substituting values

b) 10 minutes

girls stopped for 10 minutes.