# Smart Radon vs Physics Answers

The clearest difference is in-app purchases: Smart Radon at none against Physics Answers's 2. Smart Radon also leads on update cadence (fortnightly vs every 3 months) and iOS requirement (9.0 vs 11.4). On price, ads and device support there is nothing between them.

Both are free to download. Physics Answers sells 2 in-app purchases, starting at $9.99 per month. Smart Radon asks for nothing beyond the download.

Smart Radon ships an update fortnightly, Physics Answers every 3 months. The most recent releases landed on September 16, 2026 and September 9, 2026 respectively.

## The numbers

| Metric | Smart Radon | Physics Answers |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | **Fortnightly** | Every 3 months |
| Size | 38 MB | 111 MB |
| Requires iOS | **9.0** | 11.4 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Elysian Software](https://appshunter.io/developer/1361575836) | [Biobrain Learning Pty Ltd](https://appshunter.io/developer/1371680532) |

## What reviewers say

### Smart Radon

[App page](https://appshunter.io/ios/app/smart-radon/id1361575838)

**Features:** macOS Compatibility

**In-app purchases:** none


### Physics Answers

[App page](https://appshunter.io/ios/app/physics-answers-ap-physics/id1510694550)

**Features:** macOS Compatibility

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| All Content | $9.99 | per month |
| All Content | $49.99 | per year |


## Frequently asked questions

### Is Smart Radon free?

Smart Radon is free to download, with no in-app purchases.

### Is Physics Answers free?

Physics Answers is free to download, with in-app purchases available.

### Do Smart Radon or Physics Answers have ads?

Neither Smart Radon nor Physics Answers shows ads.

### Which is updated more often, Smart Radon or Physics Answers?

Smart Radon ships an update fortnightly, and Physics Answers every 3 months. Most recently, Smart Radon was updated on September 16, 2026 and Physics Answers on September 9, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*