Two automobiles, each of mass 1000kg , are moving at the same speed, 17m/s , when they collide and stick together.

At what speed does the wreckage move if one car was driving north and one east?

1 answer

before
x momentum = 17,000 (east)
y momentum = 17,000 (north)
after
m Vx = 2000 V cos T = 17,000 still
m Vy = 2000 V sin T = 17,000 still

so
sin T = cos T so T = 45 deg and sin = cos =sqrt2 /2

2000 V (sqrt 2/2) = 17,000
V = 17 /sqrt 2 = 12 m/s