Interatomic Potentials Pre-Assessment

The questions below are meant to assess your current knowledge of the physical concepts of force and energy. Please answer these questions without looking up information anywhere. Try your best to answer these questions, but if you really have no idea, you can just say that you don't know.

Taking a pre-assessment has a few purposes. First, it can help you identify what you know and don't know at the beginning of a unit and then see what you have learned at the end. Second, it helps the instructors of the course understand what the students currently know and what they learn in the course. This can help them tailor the course to the needs of the students and improve the course in coming years.

You will only be graded on completion. Please only take ~10 minutes.

Exercise 4.1.1: Force and energy pre-assessment
Not Currently Assigned

  1. Imagine throwing a ball straight up in the air and then catching it at the same height that you threw it, as illustrated below. What forces were acting on the ball:

    1. right after it left your hand at $t=0$
    2. when it reaches the top of its trajectory at $t=1$?

    sketch of a ball being tossed

  2. Imagine a mass on a frictionless surface attached to an ideal spring oscillating as shown in the figure below between $x=1$ and $x=-1$. For the quantities of (1) force, (2) kinetic energy and (3) potential energy, identify at which x-position(s) they will be at their maximum and minimum values.

    illustration of mass attached to spring oscillating

  3. A small positively charged particle (e.g., an ion) moves towards a much more massive positively charged particle as illustrated below. Assume that the more massive particle is approximately stationary throughout the interaction. At what point on the diagram does the system of the two particles have the greatest electric potential energy?

    image of a small ion colliding with a large one

  4. You pull a spring spring that was at its equilibrium length a small distance, $d$, with a constant force of magnitude $F$. How much work did you do on the spring? How much potential energy does it have?

  5. A ball is dropped and has kinetic energy equal to $x$ joules right before hitting the ground the first time. It bounces a number of times before coming to rest. After the ball has come to rest, what happened to the kinetic energy it had?

  6. What is the relationship between force and potential energy?