A uniform beam resting on two pivots has a length L = 6.00 m and weight M = 220 lbs. The pivot under the left end exerts a normal force n1 on the beam, and the second pivot, located a distance l = 4.00 m from the end exerts a normal force n2. A woman with a weight of 130 lbs steps onto the left end of the beam and begins walking to the right. How far can the woman walk before the beam tips?

x = 4,138 m

Explanation:

For this exercise, let's use the rotational equilibrium equation.

Let's fix our frame of reference on the left side of the pivot, the positive direction for anti-clockwise rotation

         ∑ τ = 0

         n₁ 0 - W L / 2 + n₂ 4 - W_woman  x = 0

         x = (- W L / 2 + 4n2) / W_woman

Let's reduce the magnitudes to the SI System

         M = 6 lbs (1 kg / 2.2 lb) = 2.72 kg

         M_woman = 130 lbs = 59.09 kg

Let's write the transnational equilibrium equation

         n₁ + n₂ - W - W_woman = 0

         n₁ + n₂ = W + W_woman

        n₁ + n₂ = (2.72 + 59.09) 9.8

At the point where the system begins to rotate, pivot 1 has no force on it, so its relation must be zero (n₁ = 0)

          n₂ = 605,738 N

Let's calculate

         x = (-2.72 9.8 6/2 + 4 605.738) / 59.09 9.8

         x = 4,138 m

  1.the balanced   chemical equation is as below

cu +   2 ag(no)₃ → cu(no₃)₂   +2 ag

2.the   much silver   produced   is   50.9 g

step 1: find the   moles of cu

moles =   mass÷   molar mass

  from periodic table the molar mass of cu = 63.5 g/mol

moles is therefore = 15.00 g÷ 63.5 g/mol = 0.236   moles

step 2: use the mole ratio to determine the   moles of ag

from equation above   cu: ag   is 1: 2

therefore the moles of ag   =0.236   moles   x 2/1 =0.472   moles

step 3: find the mass   of ag

mass = moles x molar mass

from periodic table   the molar mass of ag =107.87 g/mol

mass   = 0.472   moles x 107.87 g/mol = 50.9 g

3.   the   much   silver   collected worth is   1.797 oz

  convert   50.9 g   to oz

that is   1 gram = 0.0353 oz

          50.9 grams =?   oz

by cross multiplication

={(50.9 grams x 0.0353 oz) / 1   gram}   =1.797 oz

see earlier