A car goes 20 mph to 10 mph in five seconds find its acceleration

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?

1.what is where an object is located 2. what is how fast an objects speed is changing 3. what is how fast an object is moving

Alarge box of mass m is pulled across a horizontal frictionless surface by a horizontal rope with tension t. a small box of mass m sits on top of the large box. the coefficients of static and