Kinetic energy lost in collision is 10 J.
<u>Explanation:</u>
Given,
Mass,
= 4 kg
Speed,
= 5 m/s
= 1 kg
= 0
Speed after collision = 4 m/s
Kinetic energy lost, K×E = ?
During collision, momentum is conserved.
Before collision, the kinetic energy is

By plugging in the values we get,

K×E = 50 J
Therefore, kinetic energy before collision is 50 J
Kinetic energy after collision:


Since,
Initial Kinetic energy = Final kinetic energy
50 J = 40 J + K×E(lost)
K×E(lost) = 50 J - 40 J
K×E(lost) = 10 J
Therefore, kinetic energy lost in collision is 10 J.