Feature spec
Goal: Send a clear invoice after finishing a job.
- Add a client, line items, a due date, and payment instructions.
- Preview the total before exporting a PDF.
- Keep an editable draft if export fails.
App Overview
Physics Formulas
From the success of Maths Formulas app, Physics Formulas has been developed and released to help users quickly refer to any Physics formulas for their study and work
$0.99 · In-app purchases
PRICE
$0.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 5.0
1 ratings · Top 5%
Evidence scope: No current overall US chart position is available. Category-chart positions shown in discovery are a separate scope. Revenue is a directional model estimate, not verified earnings.
Build your own version
Build Kit
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A product spec, screen plans, and build steps for your coding agent.
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What's included15 files
A product spec, phased build plan, differentiation notes, and screen references.
- START_HERE
- AGENTS
- EVIDENCE
- SPEC
- BUILD_PLAN
- DIFFERENTIATION
- skills/
- screens/
Preview a sample Build Kit No email needed
Illustrative example: an invoice app for independent contractors. Your kit is tailored to the app you choose; this is not its generated content.
Screen plan
Invoice editor: Client at the top, editable line items in the middle, total and preview action at the bottom.
States: Empty draft, validation errors beside each field, exporting, and a retry action that preserves the draft.
Differentiate and validate
Hypothesis: Contractors need faster repeat invoices more than more templates.
First experiment: Test duplicating a previous job with five contractors. Watch where they hesitate before expanding the feature set.
The full kit adds a phased build plan, evidence notes, tool prompts, and implementation guidance. It is a plan for your coding agent, not a finished app.
Usage: Mechanics are fair game; never reuse the original name, branding, assets, or verbatim copy.
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Free quick prompt For a smaller starting point
Quick prompt
Good fit for mobile-first iOS and Android prototypes with managed app scaffolding.
// RORK SYSTEM PROMPT
Rork plan preview for Physics Formulas: map the core Education workflow, choose the smallest differentiated feature set, define the data and monetization boundaries, then prototype the riskiest user journey first.
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Opportunities
AI-GENERATED OPPORTUNITY HYPOTHESES
These are generated suggestions, not verified review quotations. Check current App Store reviews and speak with users before treating a possible gap as a requirement.
Hypothesis 1
Competitive pricing with generous free tier
Assumption to check: Expensive subscription
Validate with people who use this workflow before building.
Hypothesis 2
Focus on most-requested features first
Assumption to check: Missing features
Validate with people who use this workflow before building.
Hypothesis 3
Optimize for 60fps, fast load times
Assumption to check: Poor performance
Validate with people who use this workflow before building.
App evidence
Original App Store material. Ratings and screenshots describe the existing app, not proof of demand for your version.
App Store description
From the success of Maths Formulas app, Physics Formulas has been developed and released to help users quickly refer to any Physics formulas for their study and work. This app displays most popular formulas in seven categories: - Mechanics - Electricity - Thermal physics - Periodic motion - Optics - Atomic physics - Constants This app has all functions to help users use the app conveniently - Tools: users can input data and the app will calculate some popular physics problems. - Supporting multiple languages: it's the best to read in your mother language as well as in English to expand your language skills. In this version, there are 15 languages: English, Vietnamese, Chinese (Trad/Simp), Turkish, Spanish, German, French, Portuguese, Russian, Indonesian, Persian, Italian, Hindi and Arabic. - Favorite folder: save frequently used formulas in a favorite folder to quickly access to them. - Sharing: touch and share a formula to friends via message, email or Facebook. - Searching: users can type key words in top of the screen to quickly find a formula. - Add your own formulas or notes in "Favorite" section. - Add your own customized tools in "Tools" section (unlimited number of formulas and variables for Full version). Compare to the Free version, this Full version does not have ad-banner and has more tools. More content will be added later exclusively for Full version. This is the essential app for everybody especially students, engineers and scientists.
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Screenshots
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Build scope
Plan a focused first version with your coding agent. These are planning assumptions, not a delivery guarantee.
Define the first version
Choose one audience and one core workflow. Use the kit to agree on its screens, data, and acceptance criteria before building.
Set boundaries
Decide which secondary features, integrations, and platform support can wait. Your version does not need to reproduce everything in the original.
Check the hard parts
Validate external services, specialist technology, data access, and ongoing costs for your chosen scope.
SUGGESTED BUILD STACK
React Native
Expo
Supabase
RevenueCat
BUILD KIT DIFFICULTY
Intermediate
From the Build Kit assessment.
A reliable timeline needs an agreed scope and a technical check. Ask your agent to estimate the phases in BUILD_PLAN.md after that review.
