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## Homework Statement

In deep space a 7.0 kg rubber ball moving along the x-axis with a speed of 20 m/s collides ELASTICALLY with another ball of mass = 25 kg. After the collision the 7.0kg rubber ball's velocity is directed in the positive y axis. Find the final speed of the 7 kg ball, as well as the VELOCITY of the 25 kg ball (speed and direction)

## Homework Equations

m

_{1}v

_{1}= m

_{1}v

_{1f}+m

_{2}v

_{2f}

1/2m

_{1}v

_{1}

^{2}= 1/2m

_{1}v

_{1}

_{f}

^{2}+1/2m

_{2}v

_{2}

_{f}

^{2}

## The Attempt at a Solution

so i know that because the smaller mass is afterwards directed in the positive y direction, that all of its x momentum is transferred to the bigger mass. ive found a velocity for the x component of the bigger mass, however im stucking finding the y component, which in turn would give me the over all final velocity, which i can use to calculate the angle as well as the final speed of the smaller mass. Would be greatly appreciated if someone could point out the extra equation im missing. Basically what i have so far boils down to these equations:

m

_{1}v

_{1x}= m

_{2}v2

_{finalx}and i work out the x component of the larger mass to be 140/25 m/s

the other equation i have is for the y direction and that is :

-m

_{2}v

_{2fy}= m

_{1}v

_{1fy}

i know i somhow need to use the energy conservation formula but im just not seeing it.

Thanks a lot in advance for you help and time guys.