A 4-kg toy car with a speed of 5 m/s collides head-on with a stationary 1-kg car. After the collision, the cars are locked together with a speed of 4 m/s. How much kinetic energy is lost in the collision?

Kinetic energy lost in collision is 10 J.

Explanation:

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.

u=13

v=30

s/t=u+1\2at

=13+431/2

=13+265.5

=278.5