2011 district 1

[Salvadoramerican]

An elevator in a skyscraper is allow to reach a maximum speed of 3.7 m/s. WHat is the magnitude of the tension in the cable in order to stop the elevator in a distance of 2.7m while traveling downwards at max speed?

At 350 K, [unparseable or potentially dangerous latex formula] is .14 for this reaction 2BrCl(g) to [unparseable or potentially dangerous latex formula] An equilibrium mixture at this temperature contains equal concentration of bromine and chlorine, .0250 mol/L. What is the equilibrium concentration of BrCl?

WHat volume of .45M HCL solution willl be required to neutralize completely 500mL of a 1.2M solution of barium hydroxide?

[nsguy1350]

On the second one, I believe that [unparseable or potentially dangerous latex formula], so plug in the concentrations (where [x]) is the concentration of x, and solve for the concentration of BrCl2.
BrCl2 is squared because of the coefficient. You put the coefficients as the powers, and put product of concentrations of reactants over the same for products.

[bradp]

An elevator in a skyscraper is allow to reach a maximum speed of 3.7 m/s. WHat is the magnitude of the tension in the cable in order to stop the elevator in a distance of 2.7m while traveling downwards at max speed?


Kinematics:
vf^2=vi^2+2ad
0^2=3.7^2+2*a*2.7
a= -2.53 m/s^2

Forces on the elevator:
F_y = T - mg = ma
T - mg = m(2.53)
T = mg + m(2.53) = m(g+2.53)

Plug in the mass of the elevator (should be given) and you can get the tension. The acceleration 2.53 is positive in the second part because I called tension positive. Tension and acceleration are in the same direction so they have the same sign. You can also use the Work-Energy Theorem.

[darksaber21]