An elevator ascends from the ground with uniform speed. a time tį later, a boy drops a marble through a hole in the floor. a time t2 after that (i. e. ti +t2 after start) the marble hits the ground. find an expression for the height of the elevator at time ti. (local gravity is g.) what checks can you make?

Explanation:

Let Ye be the position of the elevator, Ve be the velocity of the elevator and Ym the position of the marble. We know that:

  Since the marble hits the ground at T2, Ym=0m

Replacing Ye into the equation for Ym:

  Solving for Ve:

 Replcaing this value into Ye:

If we check units of Ye expression, they must be distance units.

most of them using statistics and defining how things are being measured

  the grams     of oxygen gas   that can be produced     is 20.6   grams of o₂

calculation

2liclo₃ →   2 licl + 3 o₂

step 1:   find the moles of liclo₃

moles = mass÷ molar mass

from periodic table the molar mass of liclo₃ =6.9 +35.5   +(16 x3) =90.4 g/mol

moles=38.7 g÷90.4 g/mol=0.4281   moles

step 2:   use the   mole ratio   to calculate the moles of o2

from equation above, liclo₃: o₂   is 2: 3  

therefore the moles of   o₂=0.4281 moles x3/2 =0.6422   moles

step 3: find mass   of o₂

mass= moles x molar mass

from periodic table the   molar mass of   o₂ = 16 x2= 32 g/mol

mass=0.6422   moles   x   32 g/mol = 20.6 grams of o₂