Question

A blue puck has a velocity of 0i – 3j m/s and a mass of 4 kg. A gold puck has a velocity of 12i – 5j m/s and a mass of 6 kg. What is the kinetic energy of the system?

Answer 1

By definition, the kinetic energy is given by:
 K = (1/2) * m * v ^ 2
 where
 m = mass
 v = speed
 We must then find the speed of both objects:
 blue puck
 v = root ((0) ^ 2 + (- 3) ^ 2) = 3
 gold puck
 v = root ((12) ^ 2 + (- 5) ^ 2) = 13
 Then, the kinetic energy of the system will be:
 K = (1/2) * m1 * v1 ^ 2 + (1/2) * m2 * v2 ^ 2
 K = (1/2) * (4) * (3 ^ 2) + (1/2) * (6) * (13 ^ 2)
 K =  525 J
 answer
 The kinetic energy of the system is 525 J