You can stick stickers on a BMX helmet that has a smooth, hard outer shell. This type of helmet provides a good surface for stickers to adhere to securely. However, you should not stick stickers on a BMX helmet with a soft or flexible outer shell, as the stickers may not adhere properly and could potentially compromise the helmet's safety features. It's important to always follow the manufacturer's guidelines for decorating your helmet to ensure it remains safe for use. **

BMX is not prohibited in general, but it may be restricted in certain areas such as private property, parks, or public spaces where it is not allowed. It is important to check the rules and regulations of the specific location before riding BMX to avoid any potential issues or fines. Overall, BMX is a popular sport and recreational activity that is widely enjoyed by many people. **

Yes, a full-face helmet is suitable for a 6-year-old BMX beginner who wants to learn tricks. It provides maximum protection for the head, face, and jaw in case of falls or crashes while attempting tricks. Safety should always be a top priority when engaging in BMX activities, especially for young riders who are still learning and developing their skills. A full-face helmet will give parents peace of mind knowing their child is well-protected while they explore and enjoy their BMX journey. **

Gamma radiation does not have mass. Gamma radiation consists of high-energy photons, which are massless particles. While gamma radiation can transfer energy and momentum when interacting with matter, it does not possess any mass itself. **

A gamma spectrum is a visual representation of the energy levels and intensities of gamma rays emitted from a radioactive source. It is typically obtained using a gamma spectrometer, which measures the energy of gamma rays and creates a spectrum showing the distribution of energies. This spectrum can be used to identify the specific radioactive isotopes present in a sample, as each isotope emits gamma rays at characteristic energy levels. Gamma spectra are commonly used in nuclear physics, environmental monitoring, and medical imaging. **

The choice between a roller helmet and a motocross helmet depends on the activity you will be engaging in. If you are rollerblading or skateboarding, a roller helmet would be more suitable as it is designed for those specific sports and provides adequate protection for impacts common in those activities. On the other hand, if you are riding a motorcycle or participating in motocross, a motocross helmet would be the better option as it offers additional protection for higher speeds and more intense impacts. It is important to choose the helmet that is designed for the specific activity you will be doing to ensure maximum safety. **

The choice between a ski helmet and a riding helmet depends on the activity you are participating in. If you are skiing, a ski helmet is designed to provide protection against the specific risks associated with skiing, such as collisions with other skiers or obstacles. On the other hand, if you are horseback riding, a riding helmet is designed to protect against the risks associated with horseback riding, such as falls from a horse. It's important to choose the appropriate helmet for the specific activity to ensure the best protection. **

Based on the image provided, it appears that the BMX chainring is not bent. The chainring looks to be in good condition with no visible signs of warping or bending. It seems to be straight and properly aligned with the rest of the bike's components. **