2012 TMSCA State Questions

[nsguy1350]

23. There are two naturally occurring isotopes of antimony. [unparseable or potentially dangerous latex formula]Sb has an isotopic mass of 120.9038 amu and has a natural abundance of 57.25%. The isotopic mass of the other isotope is 122.00 + [unparseable or potentially dangerous latex formula], where [unparseable or potentially dangerous latex formula]

Ans: .88 amu

How is this not .9136? The equation I got was [unparseable or potentially dangerous latex formula], which gives [unparseable or potentially dangerous latex formula].

39. The ionization constant for water is [unparseable or potentially dangerous latex formula] at [unparseable or potentially dangerous latex formula] The standard molar enthalpy of neutralization of a strong acid by a strong base is [unparseable or potentially dangerous latex formula]. What is the pH of pure water at [unparseable or potentially dangerous latex formula]?

Ans: 6.5

40. You prepare .5 liters of a solution by adding .6472 moles of a weak acid, HA, to water. For HA, [unparseable or potentially dangerous latex formula]. Finally, you dilute this solution with water to a final volume of 2.0 liters. What is the pH of the diluted solution?

Ans: .86

49. A 30kg little girl runs with an initial speed of 4.0 m/s along a path tangent to the rim of a merry-go-round with radius 3.0m. The merry-go-round starts off at rest and has a moment of inertia of 500 [unparseable or potentially dangerous latex formula]. The little girl jumps onto the merry-go-round and hold on tight. Find the angular velocity of the girl and merry-go-round together. You may neglect any dissipative forces.

Ans: .47 rad/s

I tried using conservation of angular momentum and conservation of energy, but I didn't get an answer. I don't know when I should use these in rotational motion problems, but I'm trying to learn. How should I have approached this problem?

56. A circular wire loop of radius R, mass m and a current I lies on a horizontal surface. There is a horizontal magnetic field B. How large can the current I be before the edge of the loop will lift off the surface?

Ans: mg/([unparseable or potentially dangerous latex formula]RB)

I got the correct answer, but I chose it after getting [unparseable or potentially dangerous latex formula]. Since [unparseable or potentially dangerous latex formula], I got [unparseable or potentially dangerous latex formula]. Why is this wrong?

58. Two slits each have a width of a = .015mm are separated by a distance d = .060 mm and are illuminated by light of wavelength [unparseable or potentially dangerous latex formula] = 625 nm. How any bright fringes are seen in the central diffraction maximum?

Ans: 7

Any help would be greatly appreciated!

[101dalmatians]

nsguy has questions? Again? :O nsguy! This is surprising once again...
Hey - since you brought up the topic of TMSCA STATE...
On Science, how many questions on average can you do just with your knowledge of pre ap Physics - like until Light/Sound?
Of course we will be learning more but this is how much we have coered in class... so thats why I wanted to know..
This is cuz if I get like a 34 in invitationals then I wonder about Physics at State - I hope it is not gonna be sad stuff...

[darksaber21]