Question

A 1450-kg car moving east at 17.0 m/s collides with a 1880-kg car moving south at 15.0 m/s, and the two cars connect together.

How much kinetic energy was converted to another form during the collision? kJ

Answer 1

here,

the mass of car 1 , m1 = 1450 kg has initial speed , u1 = 17 m/s i

the mass of seccond car , m2 = 1880 kg has initial speed , u2 = - 15 m/s j

let the final speed of combo be v

using conservation of momentum

m1 * u1 + m2 * u2 = (m1 + m2) * v

1450 * 17 i - 1880 * 15 j = ( 1450 + 1880) * v

v = 7.4 i m/s - 8.47 j m/s

the final speed , |v| = sqrt(7.4^2 + 8.47^2) = 11.25 m/s

the kinetic energy converted to another form during the collision , dKE = KEf - KEi

dKE = 0.5 * ( m1 * u1^2 + m2 * v2^2 - (m1 + m2) * v^2)

dKE = 0.5 * ( 1450 * 17^2 + 1880 * 15^2 - ( 1450 + 1880) * 11.25^2)

dKE = 210.3 KJ

the kinetic energy converted to another form during the collision is 210.3 KJ