Apear hangs in a tree at a height of 1.8 m. the pear has a mass of 0.2 kg. the pear falls out of the tree and lands on the ground. (use correct units in all answers.)

a. how much gravitational potential energy does the pear have before it falls?

b. how much kinetic energy does the pear have when it reaches the ground?

c. how fast is the pear moving when it hits the ground?

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.