Answer:
Lost in kinetic energy = 12 J
Explanation:
From the law of conservation of momentum,
Total momentum before collision = Total momentum after collision
mu+m'u' = V(m+m')..................................... Equation 1
Where m = mass of first body, u = initial of the first body, m' = mass of the second body, u' = initial velocity of the second body, V = common velocity.
Making V the subject of the equation,
V = mu+m'u'/(m+m')........................... Equation 2
Where m = 2.0 kg, m' = 2.0 kg, u = 4.0 m/s, u' = 0 m/s ( stationary).
Substitute into equation 2
V = (2×4 + 2×0)/(2+2)
V = 8/4
V = 2 m/s.
Total kinetic energy before collision = 1/2mu² = 1/2(2)(2)² = 16 J.
Total Kinetic energy after collision = 1/2V²(m+m') = 1/2(2²)(4) = 4 J.
Thus
Lost in kinetic energy = 16 - 4
Lost in kinetic energy = 12 J
