Is kinetic energy conserved?
–How much kinetic energy was lost? If the result is to be expressed in joules, we better convert km/hr to meters/second: 1 km/hr = (1000 meter/3600 sec) = 0.27777 m/s Initial velocities: v1 = 11.111 m/s v2 = 5.5555 m/s Final velocity v3 = 1.3889 m/s Kinetic energy =1/2 m v2 KE of the car (1/2) 1500 (11.111)2 = 92, 593 KE of the truck (1/2) 4500 (5.5555)2 = 69,444 joule Total kinetic energy entering the collision 162,037 joule Final KE (1/2) 6000 (1.3889)2 = 5,787 joule Loss 156,250 joule –Where did the lost energy go? It probably went into heat. –(Optional) “Humongous Airlines” publicized the smooth ride of its new “steadijet” airliner by installing a billiards table in its first class cabin. While the plane is flying at a steady velocity v0, do collisions of two billiard balls in it conserve momentum? Yes, they do –Which velocities do we have to use in such a calculation–velocities relative to the airplane or to the ground? (For simplicity, assume the balls collide head-on and mo
