Help with 5,6

Question 5 A truck with a mass of 4.00 x 10 kg is travelling at 27.78 m/s. If the driver reduces the truck's speed to 16.67 m/s, then the truck's kinetic energy has changed by A. -2.22x 10' J B. -9.88 x 10' J C. -3.20 x10' J D. -1.28x108 J OA O B OC OD Question 6 A 2 000 g artillery shell is shot vertically upward. It has 3.60x10' J of kinetic energy as it leaves the gun on the ground. Ignoring air resistance, the height to which the shell will rise is m. (Record your answer to three significant digits.) This is a conservation of energy problem: all of the initial Ex will become potential energy at the top (we're ignoring air resistance, of course)