Two 2.0 kg bodies, a and b, collide. the velocities before the collision are
v→a=(15i^+30j^) m/s
and
v→b=(−10i^+5.0j^) m/s
. after the collision,
v→a=(−5.0i^+20j^) m/s
. what are (a) the final velocity of b and (b) the change in the total kinetic energy (including sign)?

Explanation:

Given

mass of body A

mass of body

Velocity before Collision is

after collision

let and velocity of B after collision in x and y direction

conserving momentum in x direction

as thus

Conserving momentum in Y direction

thus velocity of B after collision is

(b)Change in total Kinetic Energy

Initial Kinetic Energy of A  And B

Total initial Kinetic Energy =1250 J

Final Kinetic Energy of A  And B

Final Kinetic Energy

Change

the average speed is 24.57 km/hr