A box slides across a frictionless floor with an initial speed of 1.8m/s. It encounters a rough region where the coefficient of frictionless is 0.7. What is the shortest length of rough floor will stop the box? V=1.8 uk=0.7

A2 kg ball travellng to the right with a speed of 4 m/s collidees with a 5 kg ball traveling to the left with a speed of 3 m/s. take right to be the positive direction. what is the total momentum of the two balls before they collide? what is the total momentum of the two balls after they collide?

Gunpowder residue is most likely to show up where on a shooters hands

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?