A 2000 kg car travelling at 20m/s collides with a 1000 kg car at rest at a stop sign. If the 2000 kg car has a velocity of 6.67 m/s after the collision, find the velocity of the 1000 kg after the collision

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?

Alfred pushes on a heavy box, but cannot move it. the box has a lot of inertia motion friction gravity

At very high pressures, gases become and will eventually a) more dense; become hotter b) more dense; change to a liquid or solid c) less dense; combust d) less dense; turn into a liquid