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A 15.0 kg object is moving east at a velocity of 7.0 m/s when it collides with a 10.0 kg statinary object. After the collision the 15.0 object is travelling at a velocity of 4.2 m/s 20.0° S of E.

What is teh velocity of the 10.0 kg object after the collsion.

so far this is what i did, can you please tell me what i am doing worng? Thank-you.

15 kg object → a y→y component

10 kg object → b x→x component

Pa + Pb = P'a + P'b

Before Collision

Pa=mv

Pa=(15.0 kg)(7.0 m/s E)

Pa=105 Kgm/s

After Collsion

P'a=mv

P'a=(15.0 Kg)(4.2 m/s 20° S of E)

P'a=63 Kgm/s

P'b=mv

P'b=(10.0 Kg)(v)

P'b=?

Sin20 = P'ay/63 kgm/s

P'ay=21.5 kgm/s

Cos20°=P'ax / 63 kgm/s

P'ax = 59.2 kgm/s

Px=Squareroot[(105 kgm/s)^2 - (21.5 kgm/s)^2]

Px=102.8 kgm/s

P'bx=102.8 kg m/s - 59.2 kgm/s

P'bx= 43.6 kgm/s

P'b= squareroot[(43.6 kgm/s)^2 + (21.5 kgm/s)^2]

P'b= 48.6 kgm/s

P'b=mv

v=P'b/m

v=(48.6 kgm/s) / (10.0kg)

v= 4.86 m/s

CosX=(43.6 kgm/s)/(48.6 kgm/s)

X= 26° N of E

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# Homework Help: What is the velocity after the collision?

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