AP Physics · F=ma · USAPhO
Find the physics model
behind each miss.
FirstPrinciples maps each diagnostic choice to a named reasoning trap, then sends you to the exact Atlas entry and ladder rung that repairs it.
For students working from AP mechanics toward F=ma and USAPhO. Practice sites tell you what you missed — this maps why.
Live example
Watch one miss get diagnosed.
A real item from the diagnostic — a car rounding a flat curve at constant speed. Pick any answer. The bench traces your choice to a misconception code, the Atlas entry that explains it, and the ladder rung that repairs it.
A car rounds a flat curve at constant speed. The direction of the net force on the car is:
Select an answer. The bench traces it through the correction loop. No score kept.
awaiting answer▊
select a choice below to acquire a signal
Expert-coded distractors turn answer choices into evidence; written-work review belongs in the cohort layer.
The correction loop
Every miss runs through the same six steps.
Wrong choice → misconception code → report → atlas entry → ladder rung. The same coding rules power the report, Atlas links, and recommendations.
- 1Answer patterndiagnose
- 2Misconception code
- 3Diagnostic reportexplain
- 4Error Atlas entry
- 5Recommended rungrepair
- 6Progress data
Three surfaces
Diagnosis, atlas, ladder — wired together.
Practice alone rehearses mistakes. Here, each attempt decides what you read next and which problem you work next.
Your answer pattern, decoded
Each wrong answer maps to a specific reasoning trap — not just “incorrect,” but why you picked that one.
Run the diagnostic →66 catalogued misconceptions
Why the wrong answer felt right, and the physics that replaces it.
Open the Atlas →57 problems, 3 ladders
One new idea per rung. From a single force balance up to Olympiad-level reasoning.
View the ladder →Verified reach
Where the numbers come from.
65 of 19,185 reached the verified cohort. 45 matched pre/post pairs.
Does knowing which reasoning step broke actually help more than doing another practice set?
Baseline diagnostic, targeted ladder work, held-out follow-up, paired comparison. Results get published with the denominator attached.