A 5kg block rests on a rough surface (μs=0.5, μk=0.3 ). A 20 N force at an angle of 30o above the horizontal is applied to the block. Calculate the frictional force acting on the body.

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.