what is the speed of the 1.4 kg object immediatly after the collision?

Question

a 1.6 kg object moving at a speed of 7 m/s strikes a 1.4 kg object initially at rest. immediatly after the collision, the 1.6 kg object has a velocity of 1.4 m/s directed 31 degrees from its initial line of motion. what is the speed of the 1.4 kg object immediately after the collision?

Answer 1

Using conservation of momentum

the x direction

1.6*7=1.6*cos(31)*1.4+1.4*vx
(1.6*7-1.6*cos(31)*1.4)/1.4=vx
vx=6.628

since the initial y momentum was 0, the resulting y momentum sum equals 0, or

1.6*sin(31)*1.4=1.4*vy
vy=1.6*sin(31)
=0.824

The sqrt sum of the squares is the magnitude
=6.68 m/s

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