Question

10. A car with mass 1000 kg travels at 30 m/s, while a second car with mass 1500 kg travels at 20 m/s. The two cars collide in a perfectly inelastic collision. What is the final velocity (speed and direction) if the first car was travelling north and the second travelling south? If the first car were travelling north and the second were travelling east?

Answer 1

Let's take sing convention for the directions as-

NORTH is +j, SOUTH is -j, EAST is +i and WEST is -i

let's call both cars as car A and car B

mass of car A M_A = 1000 Kg

mass of car B M_B =  15000 Kg

first cast

velocity of car A V_A = 30 (j) m/sec

velocity of car B V_B= 20 (-j) m/sec

let the velocit after collision be V

so by conservaton of liear momentum

putting values gives

V= 0 j m/sec

which mean both at cars stops after collision

For case 2

now V_A= 30 (j) and V_B= 20(i)

again by conservation of linear momentum

the magnitude of the velocity is =

direction is north east