One mole of Strontium-90 is decaying with a half life of 28. years. After 61. years, how much Strontium is left and what is its activity?
What will be an ideal response?
0.22 mole; 5.5 × 10-3 mole/yr = 1.0 × 1014 Becquerel = 2.8 × 103 Curie
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Briefly describe what you would see if your friend plunged into a black hole. Assume you are watching from orbit of the black hole and have a telescope powerful enough so that you can see him clearly as he falls.
What will be an ideal response?
Hubble's constant is related to the age of the universe, but the precise relationship depends on the way in which the expansion rate changes with time
For a given value of Hubble's constant today (such as 24 km/s/Mly), the age of the universe is oldest if what is true? A) The expansion rate has remained nearly constant with time (a coasting universe). B) The expansion rate has slowed by the amount expected for a universe with the critical density (a critical universe). C) The expansion rate has been increasing with time (an accelerating universe). D) The expansion rate is slowing dramatically with time (a recollapsing universe).
Consider the motion of a 1.00-kg particle that moves with potential energy given by U(x) = (-2.00 J?m)/x + (4.00 J?m2)/x2. Suppose the particle is moving with a speed of 3.00 m/s when it is located at x = 1.00 m
What is the speed of the object when it is located at x = 5.00 m? A) 2.13 m/s B) 3.00 m/s C) 4.68 m/s D) 3.67 m/s
Which of the following individuals did not directly contribute to quantum theory?
A. Schrödinger B. Einstein C. Heisenberg D. Planck E. Roentgen