If a ball speeds up as it is rolling down a hill, the forces acting on it must be -
1. Balanced
2. Unbalanced
3. Weak
4. Strong
Need help ASAP

Modern physics a photon emitted from an excited hydrogen atom has an energy of 3.02 electron volts. which electron energy-level transition would produce this photon? a. n=1 to n=6 b. n=2 to n=6 c. n=6 to n=1 d. n=6 to n=2 i chose b but the correct answer is d can someone tell me why? and what's the difference?