AP Physics 1 2.1: Systems and Interactions

For identifying a physical factor that could have affected the result

Accept one of the following:

- A physical factor in the materials used (e.g., the wheels have nonnegligible rotational inertia, the ramp was bumpy, the wheels were wobbly or not perfectly round, the base of the ramp was not level, the floor was not level.)

- A physical factor in the environment (e.g., the room was being accelerated, elevator, the experiment was performed at high elevation or on a different planet.)

- A physical error in measurement collection (e.g., time, position, or angle was measured incorrectly.)

Scoring Note: A statement of "Human error" does not earn this point.

For correctly indicating the functional dependence between the reason listed in part (c)(i) and $g_{\text {exp }}$

Accept one of the following:

- Correctly indicating the functional dependence between the physical factor in the materials used and $g_{\text {exp }}$ (e.g., if the rotational inertia of the rotating wheels is nonnegligible, the cart will have a smaller acceleration and $g_{\text {exp }}$ will be smaller.)

- Correctly indicating the functional dependence between the physical factor in the environment and $g_{\text {exp }}$ (e.g., if the experiment was performed at a high elevation, the acceleration will be smaller and $g_{\text {exp }}$ will be smaller.)

- Correctly indicating the functional dependence between the physical error in the measurement collection and $g_{\text {exp }}$ (e.g., if the angle of the ramp is smaller than the measured value, the cart will have a smaller acceleration and $g_{\text {exp }}$ will be smaller.)

Example Response

The expression I derived for the value for $g_{\text {exp }}$ did not take into consideration that the wheels had any rotational inertia. If the wheels have rotational inertia and are rotating, the acceleration of the cart would be less than $g \sin \theta$, so the value of $g_{\text {exp }}$ would be less than $9.8 \frac{\mathrm{~m}}{\mathrm{~s}^{2}}$.

Total for part (c) 2 points