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?

Respuesta :

Kinetic energy lost in collision is 10 J.

Explanation:

Given,

Mass, [tex]m_{1}[/tex] = 4 kg

Speed, [tex]v_{1}[/tex] = 5 m/s

[tex]m_{2}[/tex] = 1 kg

[tex]v_{2}[/tex] = 0

Speed after collision = 4 m/s

Kinetic energy lost, K×E = ?

During collision, momentum is conserved.

Before collision, the kinetic energy is

[tex]\frac{1}{2} m1 (v1)^2 + \frac{1}{2} m2(v2)^2[/tex]

By plugging in the values we get,

[tex]KE = \frac{1}{2} * 4 * (5)^2 + \frac{1}{2} * 1 * (0)^2\\\\KE = \frac{1}{2} * 4 * 25 + 0\\\\[/tex]

K×E = 50 J

Therefore, kinetic energy before collision is 50 J

Kinetic energy after collision:

[tex]KE = \frac{1}{2} (4 + 1) * (4)^2 + KE(lost)[/tex]

[tex]KE = 40J + KE(lost)[/tex]

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.