What is the velocity of a 4 kg object that possesses 18 j of kinetic energy

In a system, when potential energy decreases, then entropy also decreases. true false

At 20∘c, the hole in an aluminum ring is 2.800 cm in diameter. you need to slip this ring over a steel shaft that has a room-temperature diameter of 2.804 cm . 1. to what common temperature should the ring and the shaft be heated so that the ring will just fit onto the shaft? coefficients of linear thermal expansion of steel and aluminum are 12×10−6 k−1 and23×10−6 k−1 respectively.

What is friction? how does it affect the motion of an object?