Questions:
A Hillview Prep student is currently preparing for her SAT Subject Test in Physics. We started her on a test using the Smart Scoring System. What we found is quite interesting: on easy questions, she was guessing and thus making simple errors. The question on the test is below:
Relate to the following physical principles or topics. (A) pressure (B) energy (C) work (D) force (E) centripetal acceleration Select the quantity that each expression defines.
Answers:
1. C
Our student just guessed and got it wrong. Instead of guessing, we suggest using units to figure out what the physical quantity. This formula can be rewritten as:
\[/frac{(m}{t}(v  vo)\]
We have here, Kg (mass) x m^2/s^2, which is Nm (Kg m/s^2) x m, which is Joules, i.e. energy.
2. E
This formula can be used to determine the acceleration of an object in circular motion. Again, break down the units and you will see m/s^2, which is acceleration.
3. B
This formula describes the potential energy of charge q, in the presence of charge q, a distance r away.
4. A
This is just a rearrangement of the ideal gas law pv = nRT.
5. D
Doing the units, we get, (Kg.(m/s))/s, or Kg m/s^2, which is N, e.g. the unit for force.
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