This is the audio exerpt of ʊ spoken within a word. It may sound a little short or unclear, but that's exactly how it's in the real context. For more details, read the below explanation of pronunciation and listen example words that contain ʊ by pressing the word buttons.
1. Open your mouth for about 20%.
2. Relax your lips.
3. Raise the utmost back of your tongue without touching the back palate.
4. Push air from lungs while vibrating vocal cords.